prompt_front: Now, answer the following question based on the text below, only give me the answer and do not output any other words.

Question: What types of data did the authors use in their experiments?

Read the following text and answer briefly.

Context 1: \section{Introduction}
\label{sec:introduction}

Probabilistic models have proven to be very useful in a lot of applications in signal processing where signal estimation is needed \cite{rabiner1989tutorial,arulampalam2002tutorial,ji2008bayesian}  Some of their advantages are that 1) they force the designer to specify all the assumptions of the model, 2) they provide a clear separation between the model and the algorithm used to solve it, and 3) they usually provide some measure of uncertainty about the estimation 

On the other hand, adaptive filtering is a standard approach in estimation problems when the input is received as a stream of data that is potentially non-stationary  This approach is widely understood and applied to several problems such as echo cancellation \cite{gilloire1992adaptive}, noise cancellation \cite{nelson1991active}, and channel equalization \cite{falconer2002frequency} 

Although these two approaches share some underlying relations, there are very few connections in the literature  The first important attempt in the signal processing community to relate these two fields was the connection between a linear Gaussian state-space model (i e  Kalman filter) and the RLS filter, by Sayed and Kailath \cite{sayed1994state} and then by Haykin \emph{et al } \cite{haykin1997adaptive}  The RLS adaptive filtering algorithm emerges naturally when one defines a particular state-space model (SSM) and then performs exact inference in that model  This approach was later exploited in \cite{van2012kernel} to design a kernel RLS algorithm based on Gaussian processes 

A first attempt to approximate the LMS filter from a probabilistic perspective was presented in \cite{park2014probabilistic}, focusing on a kernel-based implementation  The algorithm of \cite{park2014probabilistic} makes use of a Maximum a Posteriori (MAP) estimate as an approximation for the predictive step  However, this approximation does not preserve the estimate of the uncertainty in each step, therefore degrading the performance of the algorithm 

In this work, we provide a similar connection between state-space models and least-mean-squares (LMS)  Our approach is based on approximating the posterior distribution with an isotropic Gaussian distribution  We show how the computation of this approximated posterior leads to a linear-complexity algorithm, comparable to the standard LMS  Similar approaches have already been developed for a variety of problems such as channel equalization using recurrent RBF neural networks \cite{cid1994recurrent}, or Bayesian forecasting \cite{harrison1999bayesian}  Here, we show the usefulness of this probabilistic approach for adaptive filtering 

The probabilistic perspective we adopt throughout this work presents two main advantages  Firstly, a novel LMS algorithm with adaptable step size emerges naturally with this approach, making it suitable for both stationary and non-stationary environments  The proposed algorithm has less free parameters than previous LMS algorithms with variable step size \cite{kwong1992variable,aboulnasr1997robust,shin2004variable}, and its parameters are easier to be tuned w r t  these algorithms and standard LMS  Secondly, the use of a probabilistic model provides us with an estimate of the error variance, which is useful in many applications 

Experiments with simulated and real data show the advantages of the presented approach with respect to previous works  However, we remark that the main contribution of this paper is that it opens the door to introduce more Bayesian machine learning techniques, such as variational inference and Monte Carlo sampling methods \cite{barber2012bayesian}, to adaptive filtering \\


\section{Probabilistic Model}

Throughout this work, we assume the observation model to be linear-Gaussian with the following distribution,

\begin{equation}
p(y_k|{\bf w}_k) = \mathcal{N}(y_k;{\bf x}_k^T {\bf w}_k , \sigma_n^2),
\label{eq:mess_eq}
\end{equation}
where  $\sigma_n^2$ is the variance of the observation noise, ${\bf x}_k$ is the regression vector and ${\bf w}_k$ is the parameter vector to be sequentially estimated, both $M$-dimensional column vectors 


In a non-stationary scenario, ${\bf w}_k$ follows a dynamic process  In particular, we consider a diffusion process (random-walk model) with variance $\sigma_d^2$ for this parameter vector:


\begin{equation}
p({\bf w}_k|{\bf w}_{k-1})= \mathcal{N}({\bf w}_k;{\bf w}_{k-1}, \sigma_d^2 {\bf I}),
\label{eq:trans_eq}
\end{equation}
where $\bf I$ denotes the identity matrix  In order to initiate the recursion, we assume the following prior distribution on ${\bf w}_k$

\begin{equation}
p({\bf w}_0)= \mathcal{N}({\bf w}_0;0, \sigma_d^2{\bf I}) \nonumber
\end{equation}

\section{Exact inference in this model: Revisiting the RLS filter}

Given the described probabilistic SSM, we would like to infer the posterior probability distribution $p({\bf w}_k|y_{1:k})$ 
Since all involved distributions are Gaussian, one can perform exact inference, leveraging the probability rules in a straightforward manner  The resulting probability distribution is
\begin{equation}
p({\bf w}_k|y_{1:k}) =  \mathcal{N}({\bf w}_k;{\bf\boldsymbol\mu}_{k}, \boldsymbol\Sigma_{k}), \nonumber
\end{equation}
in which the mean vector ${\bf\boldsymbol\mu}_{k}$ is given by
\begin{equation}
{\bf\boldsymbol\mu}_k = {\bf\boldsymbol\mu}_{k-1} + {\bf K}_k (y_k - {\bf x}_k^T {\bf\boldsymbol\mu}_{k-1}){\bf x}_k, \nonumber
\end{equation}
where we have introduced the auxiliary variable
\begin{equation}
{\bf K}_k = \frac{ \left(\boldsymbol\Sigma_{k-1} + \sigma_d^2 {\bf I}\right)}{{\bf x}_k^T  \left(\boldsymbol\Sigma_{k-1} + \sigma_d^2 {\bf I}\right)  {\bf x}_k + \sigma_n^2}, \nonumber
\end{equation}
and the covariance matrix $\boldsymbol\Sigma_k$ is obtained as
\begin{equation}
\boldsymbol\Sigma_k = \left( {\bf I} -  {\bf K}_k{\bf x}_k {\bf x}_k^T \right) ( \boldsymbol\Sigma_{k-1} +\sigma_d^2), \nonumber
\end{equation}
Note that the mode of $p({\bf w}_k|y_{1:k})$, i e  the maximum-a-posteriori estimate (MAP), coincides with the RLS adaptive rule
\begin{equation}
{{\bf w}}_k^{(RLS)} = {{\bf w}}_{k-1}^{(RLS)} + {\bf K}_k (y_k - {\bf x}_k^T {{\bf w}}_{k-1}^{(RLS)}){\bf x}_k  
\label{eq:prob_rls}
\end{equation}
This rule is similar to the one introduced in \cite{haykin1997adaptive} 

Finally, note that the covariance matrix $\boldsymbol\Sigma_k$ is a measure of the uncertainty of the estimate ${\bf w}_k$ conditioned on the observed data $y_{1:k}$  Nevertheless, for many applications a single scalar summarizing the variance of the estimate could prove to be sufficiently useful  In the next section, we show how such a scalar is obtained naturally when $p({\bf w}_k|y_{1:k})$ is approximated with an isotropic Gaussian distribution  We also show that this approximation leads to an LMS-like estimation 
 


\section{Approximating the posterior distribution: LMS filter }

The proposed approach consists in approximating the posterior distribution $p({\bf w}_k|y_{1:k})$, in general a multivariate Gaussian distribution with a full covariance matrix, by an isotropic spherical Gaussian distribution 

\begin{equation}
\label{eq:aprox_post}
\hat{p}({\bf w}_{k}|y_{1:k})=\mathcal{N}({\bf w}_{k};{\bf \hat{\boldsymbol\mu}}_{k}, \hat{\sigma}_{k}^2 {\bf I} ) 
\end{equation}

In order to estimate the mean and covariance of the approximate distribution $\hat{p}({\bf w}_{k}|y_{1:k})$, we propose to select those that minimize the Kullback-Leibler divergence with respect to the original distribution, i e , 

\begin{equation}
\{\hat{\boldsymbol\mu}_k,\hat{\sigma}_k\}=\arg \displaystyle{  \min_{\hat{\boldsymbol\mu}_k,\hat{\sigma}_k}} \{ D_{KL}\left(p({\bf w}_{k}|y_{1:k}))\| \hat{p}({\bf w}_{k}|y_{1:k})\right) \}  \nonumber
\end{equation}

The derivation of the corresponding minimization problem can be found in Appendix A  In particular, the optimal mean and the covariance are found as
\begin{equation}
{\hat{\boldsymbol\mu}}_{k} = {\boldsymbol\mu}_{k};~~~~~~ \hat{\sigma}_{k}^2 = \frac{{\sf Tr}\{ \boldsymbol\Sigma_k\} }{M} 
\label{eq:sigma_hat}
\end{equation}


We now show that by using \eqref{eq:aprox_post} in the recursive predictive and filtering expressions we obtain an LMS-like adaptive rule  First, let us assume that we have an approximate posterior distribution at $k-1$, $\hat{p}({\bf w}_{k-1}|y_{1:k-1}) =  \mathcal{N}({\bf w}_{k-1};\hat{\bf\boldsymbol\mu}_{k-1}, \hat{\sigma}_{k-1}^2 {\bf I} )$  Since all involved distributions are Gaussian, the predictive distribution
is obtained as %
\begin{eqnarray}
\hat{p}({\bf w}_k|y_{1:k-1}) &=& \int p({\bf w}_k|{\bf w}_{k-1}) \hat{p}({\bf w}_{k-1}|y_{1:k-1}) d{\bf w}_{k-1} \nonumber\\
&=& \mathcal{N}({\bf w}_k;{\bf\boldsymbol\mu}_{k|k-1}, \boldsymbol\Sigma_{k|k-1}), 
\label{eq:approx_pred}
\end{eqnarray}
where the mean vector and covariance matrix are given by
\begin{eqnarray}
\hat{\bf\boldsymbol\mu}_{k|k-1} &=& \hat{\bf\boldsymbol\mu}_{k-1} \nonumber \\
\hat{\boldsymbol\Sigma}_{k|k-1} &=& (\hat{\sigma}_{k-1}^2 + \sigma_d^2 ){\bf I}\nonumber 
\end{eqnarray}

From \eqref{eq:approx_pred}, the posterior distribution at time $k$ can be computed using Bayes' Theorem and standard Gaussian manipulations (see for instance \cite[Ch  4]{murphy2012machine})  Then, we approximate the posterior $p({\bf w}_k|y_{1:k})$ with an isotropic Gaussian,
\begin{equation}
\hat{p}({\bf w}_k|y_{1:k}) =  \mathcal{N}({\bf w}_k ; {\hat{\boldsymbol\mu}}_{k}, \hat{\sigma}_k^2 {\bf I} ),\nonumber
\end{equation}
where 
\begin{eqnarray}
{\hat{\boldsymbol\mu}}_{k} &= & {\hat{\boldsymbol\mu}}_{k-1}+ \frac{ (\hat{\sigma}_{k-1}^2+ \sigma_d^2)  }{(\hat{\sigma}_{k-1}^2+ \sigma_d^2)  \|{\bf x}_k\|^2 + \sigma_n^2} (y_k - {\bf x}_k^T {\hat{\boldsymbol\mu}}_{k-1}){\bf x}_k  \nonumber  \\
&=& {\hat{\boldsymbol\mu}}_{k-1}+ \eta_k (y_k - {\bf x}_k^T {\hat{\boldsymbol\mu}}_{k-1}){\bf x}_k   
\label{eq:prob_lms}
\end{eqnarray}
Note that, instead of a gain matrix ${\bf K}_k$ as in Eq ~\eqref{eq:prob_rls}, we now have a scalar gain $\eta_k$ that operates as a variable step size 


Finally, to obtain the posterior variance, which is our measure of uncertainty, we apply \eqref{eq:sigma_hat} and the trick ${\sf Tr}\{{\bf x}_k{\bf x}_k^T\}= {\bf x}_k^T{\bf x}_k= \|{\bf x}_k \|^2$,

\begin{eqnarray}
\hat{\sigma}_k^2 &=& \frac{{\sf Tr}(\boldsymbol\Sigma_k)}{M} \\
&=& \frac{1}{M}{\sf Tr}\left\{ \left( {\bf I} -  \eta_k {\bf x}_k {\bf x}_k^T \right) (\hat{\sigma}_{k-1}^2 +\sigma_d^2)\right\} \\
&=& \left(1 - \frac{\eta_k \|{\bf x}_k\|^2}{M}\right)(\hat{\sigma}_{k-1}^2 +\sigma_d^2) 
\label{eq:sig_k}
\end{eqnarray}
If MAP estimation is performed, we obtain  an adaptable step-size LMS estimation

\begin{equation}
{\bf w}_{k}^{(LMS)} = {\bf w}_{k-1}^{(LMS)} + \eta_k (y_k - {\bf x}_k^T {\bf w}_{k-1}^{(LMS)}){\bf x}_k, 	
\label{eq:lms}
\end{equation}
with
\begin{equation}
\eta_k = \frac{ (\hat{\sigma}_{k-1}^2+ \sigma_d^2)  }{(\hat{\sigma}_{k-1}^2+ \sigma_d^2)  \|{\bf x}_k\|^2 + \sigma_n^2} \nonumber
\end{equation}
At this point, several interesting remarks can be made:

\begin{itemize}

\item The adaptive rule \eqref{eq:lms} has linear complexity since it does not require us to compute the full matrix $\boldsymbol\Sigma_k$ 

\item For a stationary model, we have $\sigma_d^2=0$ in \eqref{eq:prob_lms} and \eqref{eq:sig_k}  In this case, the algorithm remains valid and both the step size and the error variance, $\hat{\sigma}_{k}$, vanish over time $k$  

\item Finally, the proposed adaptable step-size LMS has only two parameters, $\sigma_d^2$ and $\sigma_n^2$, (and only one, $\sigma_n^2$, in stationary scenarios) in contrast to other variable step-size algorithms \cite{kwong1992variable,aboulnasr1997robust,shin2004variable}  More interestingly, both $\sigma_d^2$ and $\sigma_n^2$ have a clear underlying physical meaning, and they can be estimated in many cases  We will comment more about this in the next section  
\end{itemize}



\section{Experiments}
\label{sec:experiments}

We evaluate the performance of the proposed algorithm in both stationary and tracking experiments  In the first experiment, we estimate a fixed vector ${\bf w}^{o}$ of dimension $M=50$  The entries of the vector are independently and uniformly chosen in the range $[-1,1]$  Then, the vector is normalized so that $\|{\bf w}^o\|=1$  Regressors $\boldsymbol{x}_{k}$ are zero-mean Gaussian vectors with identity covariance matrix  The additive noise variance is such that the SNR is $20$ dB  We compare our algorithm with standard RLS and three other LMS-based algorithms: LMS, NLMS \cite{sayed2008adaptive}, VSS-LMS \cite{shin2004variable} \footnote{The used parameters for each algorithm are: for RLS $\lambda=1$, $\epsilon^{-1}=0 01$; for LMS $\mu=0 01$; for NLMS $\mu=0 5$; and for VSS-LMS $\mu_{max}=1$, $\alpha=0 95$, $C=1e-4$ } The probabilistic LMS algorithm in \cite{park2014probabilistic} is not simulated because it is not suitable for stationary environments 

In stationary environments, the proposed algorithm has only one parameter, $\sigma^2_n$  We simulate both the scenario where we have perfectly knowledge of the amount of noise (probLMS1) and the case where the value $\sigma^2_n$ is $100$ times smaller than the actual value (probLMS2)  The Mean-Square Deviation (${\sf MSD} = {\mathbb E} \| {\bf w}_0 - {\bf w}_k \|^2$), averaged out over $50$ independent simulations, is presented in Fig  \ref{fig:msd_statationary} 



\begin{figure}[htb]
\centering
\begin{minipage}[b]{\linewidth}
  \centering
  \centerline{\includegraphics[width=\textwidth]{results_stationary_MSD}}
\end{minipage}
\caption{Performance in terms of MSD of probabilistic LMS with both optimal (probLMS1) and suboptimal (probLMS2) compared to LMS, NLMS, VS-LMS, and RLS }
\label{fig:msd_statationary}
\end{figure}

The performance of probabilistic LMS is close to RLS (obviously at a much lower computational cost) and largely outperforms previous variable step-size LMS algorithms proposed in the literature  Note that, when the model is stationary, i e  $\sigma^2_d=0$ in \eqref{eq:trans_eq},  both the uncertainty $\hat{\sigma}^2_k$, and the adaptive step size $\eta_k$, vanish over time  This implies that the error tends to zero when $k$ goes to infinity  Fig  \ref{fig:msd_statationary} also shows that the proposed approach is not very sensitive to a bad choice of its only parameter, as demonstrated by the good results of probLMS2, which uses a $\sigma^2_n$ that is $100$ times smaller than the optimal value  


\begin{figure}[htb]
\centering
\begin{minipage}[b]{\linewidth}
  \centering
  \centerline{\includegraphics[width=\textwidth]{fig2_final}}
\end{minipage}
\caption{Real part of one coefficient of the measured and estimated channel in experiment two  The shaded area represents two standard deviations from the prediction {(the mean of the posterior distribution)} }
\label{fig_2}
\end{figure}


\begin{table}[ht]
\begin{footnotesize}
\setlength{\tabcolsep}{2pt}
\def1 5mm{1 5mm}
\begin{center}
\begin{tabular}{|l@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|c@{\hspace{1 5mm}}|}
\hline
Method &  LMS &  NLMS & LMS-2013 & VSSNLMS & probLMS & RLS \\
\hline
\hline
MSD (dB) &-28 45 &-21 07 &-14 36 &-26 90 &-28 36 &-25 97\\
\hline                                                                     
\end{tabular}
\end{center}
\caption{Steady-state MSD of the different algorithms for the tracking of a real MISO channel }
\label{tab:table_MSD}
\end{footnotesize}

\end{table}
\newpage
In a second experiment, we test the tracking capabilities of the proposed algorithm with {real} data of a wireless MISO channel acquired in a realistic indoor scenario  More details on the setup can be found in \cite{gutierrez2011frequency}  Fig  \ref{fig_2} shows the real part of one of the channels, and the estimate of the proposed algorithm  The shaded area represents the estimated uncertainty for each prediction, i e  $\hat{\mu}_k\pm2\hat{\sigma}_k$  Since the experimental setup does not allow us to obtain the optimal values for the parameters, we fix these parameters to their values that optimize the steady-state mean square deviation (MSD)  \hbox{Table \ref{tab:table_MSD}} shows this steady-state MSD of the estimate of the MISO channel with different methods  As can be seen, the best tracking performance is obtained by standard LMS and the proposed method  





\section{Conclusions and Opened Extensions}
\label{sec:conclusions}

{We have presented a probabilistic interpretation of the least-mean-square filter  The resulting algorithm is an adaptable step-size LMS that performs well both in stationary and tracking scenarios  Moreover, it has fewer free parameters than previous approaches and these parameters have a clear physical meaning  Finally, as stated in the introduction, one of the advantages of having a probabilistic model is that it is easily extensible:}

\begin{itemize}
\item If, instead of using an isotropic Gaussian distribution in the approximation, we used a Gaussian with diagonal covariance matrix, we would obtain a similar algorithm with different step sizes and measures of uncertainty, for each component of ${\bf w}_k$  Although this model can be more descriptive, it needs more parameters to be tuned, and the parallelism with LMS vanishes 
\item Similarly, if we substitute the transition model of \eqref{eq:trans_eq} by an Ornstein-Uhlenbeck process, 

\begin{equation}
p({\bf w}_k|{\bf w}_{k-1})= \mathcal{N}({\bf w}_k;\lambda {\bf w}_{k-1}, \sigma_d^2), \nonumber
\label{eq:trans_eq_lambda}
\end{equation}
a similar algorithm is obtained but with a forgetting factor $\lambda$ multiplying ${\bf w}_{k-1}^{(LMS)}$ in \eqref{eq:lms}  This algorithm may have improved performance under such a kind of autoregresive dynamics of ${\bf w}_{k}$, though, again, the connection with standard LMS becomes dimmer 

\item As in \cite{park2014probabilistic}, the measurement model \eqref{eq:mess_eq} can be changed to obtain similar adaptive algorithms for classification, ordinal regression, and Dirichlet regression for compositional data  

\item A similar approximation technique could be applied to more complex dynamical models, i e  switching dynamical models \cite{barber2010graphical}  The derivation of efficient adaptive algorithms that explicitly take into account a switch in the dynamics of the parameters of interest is a non-trivial and open problem, though the proposed approach could be useful 

\item Finally, like standard LMS, this algorithm can be kernelized for its application in estimation under non-linear scenarios 

\end{itemize}


\begin{appendices}

\section{KL divergence between a general gaussian distribution and an isotropic gaussian}
\label{sec:kl}

 We want to approximate  $p_{{\bf x}_1}(x) = \mathcal{N}({\bf x}; \boldsymbol\mu_1,\boldsymbol\Sigma_1)$ by $p_{{\bf x}_2}({\bf x}) = \mathcal{N}({\bf x}; \boldsymbol\mu_2,\sigma_2^2 {\bf I})$  In order to do so, we have to compute the parameters of $p_{{\bf x}_2}({\bf x})$, $\boldsymbol\mu_2$ and $\sigma_2^2$, that minimize the following Kullback-Leibler divergence,

\begin{eqnarray}
D_{KL}(p_{{\bf x}_1}\| p_{{\bf x}_2}) &=&\int_{-\infty}^{\infty} p_{{\bf x}_1}({\bf x}) \ln{\frac{p_{{\bf x}_1}({\bf x})}{p_{{\bf x}_2}({\bf x})}}d{\bf x} \nonumber  \\
&= &  \frac{1}{2} \{ -M + {\sf Tr}(\sigma_2^{-2} {\bf I}\cdot \boldsymbol\Sigma_1^{-1})  \nonumber \\
  & &  + (\boldsymbol\mu_2 - \boldsymbol\mu_1 )^T \sigma^{-2}_2{\bf I} (\boldsymbol\mu_2 - \boldsymbol\mu_1 )  \nonumber \\
 & &   +  \ln \frac{{\sigma_2^2}^M}{\det\boldsymbol\Sigma_1} \}   
\label{eq:divergence}
\end{eqnarray}
Using symmetry arguments, we obtain 
\begin{equation}
\boldsymbol\mu_2^{*} =\arg \displaystyle{  \min_{\boldsymbol\mu_2}} \{ D_{KL}(p_{{\bf x}_1}\| p_{{\bf x}_2}) \} = \boldsymbol\mu_1 
\end{equation}
Then, \eqref{eq:divergence} gets simplified into 

\begin{eqnarray}
D_{KL}(p_{{\bf x}_1}\| p_{{\bf x}_2}) = \frac{1}{2}\lbrace { -M + {\sf Tr}(\frac{\boldsymbol\Sigma_1}{\sigma_2^{2}}) + \ln \frac{\sigma_2^{2M}}{\det\boldsymbol\Sigma_1}}\rbrace 
\end{eqnarray}
The variance $\sigma_2^2$ is computed in order to minimize this Kullback-Leibler divergence as

\begin{eqnarray}
\sigma_2^{2*} &=& \arg\min_{\sigma_2^2} D_{KL}(P_{x_1}\| P_{x_2}) \nonumber \\
 &=& \arg\min_{\sigma_2^2}\{ \sigma_2^{-2}{\sf Tr}\{\boldsymbol\Sigma_1\} + M\ln \sigma_2^{2} \}  
\end{eqnarray}
Deriving and making it equal zero leads to

\begin{equation}
\frac{\partial}{\partial \sigma_2^2} \left[ \frac{{\sf Tr}\{\boldsymbol\Sigma_1\}}{\sigma_2^{2}} + M \ln \sigma_2^{2} \right] = \left  {\frac{M}{\sigma_2^{2}}-\frac{{\sf Tr}\{\boldsymbol\Sigma_1\}}{(\sigma_2^{2})^2}}\right|_{\sigma_2^{2}=\sigma_2^{2*}}\left  =0 \right   
\nonumber
\end{equation}
Finally, since the divergence has a single extremum in $R_+$,
\begin{equation}
\sigma_2^{2*} = \frac{{\sf Tr}\{\boldsymbol\Sigma_1\}}{M} 
\end{equation}




\end{appendices}

\vfill
\clearpage

\bibliographystyle{IEEEbib}

Context 2: Paper Info

Title: Bistability between π-diradical open-shell and closed-shell states in indeno[1,2-a]fluorene
Publish Date: Unkown
Author List: Shantanu Mishra (from IBM Research Europe -Zurich), Manuel Vilas-Varela (from Department of Organic Chemistry, Center for Research in Biological Chemistry and Molecular Materials (CiQUS), University of Santiago de Compostela), Leonard-Alexander Lieske (from IBM Research Europe -Zurich), Ricardo Ortiz (from Donostia International Physics Center (DIPC)), Igor Rončević (from Department of Chemistry, University of Oxford), Florian Albrecht (from IBM Research Europe -Zurich), Diego Peña (from Department of Organic Chemistry, Center for Research in Biological Chemistry and Molecular Materials (CiQUS), University of Santiago de Compostela), Leo Gross (from IBM Research Europe -Zurich)

Figure

Fig  1 | Non-benzenoid non-alternant polycyclic conjugated hydrocarbons a, Classical nonbenzenoid non-alternant polycyclic conjugated hydrocarbons: pentalene, azulene and heptalene b, Generation of indacenes and indenoindenes through benzinterposition and benzannelation of pentalene, respectively Gray filled rings represent Clar sextets c, Closed-shell Kekulé (left) and openshell non-Kekulé (right) resonance structures of QDMs Note that meta-QDM is a non-Kekulé molecule All indenofluorene isomers, being derived through benzannelation of indacenes, contain a central QDM moiety d, Closed-shell Kekulé (top) and open-shell non-Kekulé (bottom) resonance structures of indenofluorenes Compared to their closed-shell structures, 1 and 5 gain two Clar sextets in the openshell structure, while 2-4 gain only one Clar sextet in the open-shell structure Colored bonds in d highlight the ortho-and para-QDM moieties in the two closed-shell Kekulé structures of 5  e, Scheme of on-surface generation of 5 by voltage pulse-induced dehydrogenation of 6 (C20H14) Structures 7 and 8 represent the two monoradical species (C20H13) 
Fig  2 | Characterization of open-shell indeno[1,2-a]fluorene on bilayer NaCl/Au(111) a, DFTcalculated wave functions of the frontier orbitals of 5OS in the triplet configuration for the spin up (occupied) level (isovalue: 0 002 e -Å -3 ) Blue and red colors represent opposite phases of the wave function b, Corresponding DFT-calculated spin density of 5OS (isovalue: 0 01 e -Å -3) Blue and orange colors represent spin up and spin down densities, respectively c, Probability density of the SOMOs of 5OS (isovalue: 0 001 e -Å -3 ) d, DFT-calculated bond lengths of 5OS e, Constant-height I(V) spectra acquired on a species of 5 assigned as 5OS, along with the corresponding dI/dV(V) spectra Open feedback parameters: V = -2 V, I = 0 17 pA (negative bias side) and V = 2 V, I = 0 17 pA (positive bias side) Acquisition position of the spectra is shown in Supplementary Fig 7 f, Scheme of many-body transitions associated to the measured ionic resonances of 5OS Also shown are STM images of assigned 5OS at biases where the corresponding transitions become accessible Scanning parameters: I = 0 3 pA (V = -1 2V and -1 5 V) and 0 2 pA (V = 1 3 V and 1 6 V)  g, Laplace-filtered AFM image of assigned 5OS STM set point: V = 0 2 V, I = 0 5 pA on bilayer NaCl, Δz = -0 3Å The tip-height offset Δz for each panel is provided with respect to the STM setpoint, and positive (negative) values of Δz denote tip approach (retraction) from the STM setpoint f and g show the same molecule at the same adsorption site, which is next to a trilayer NaCl island The bright and dark features in the trilayer NaCl island in g correspond to Cl -and Na + ions, respectively Scale bars: 10 Å (f) and 5 Å (g) 
Fig  3 | Characterization of closed-shell indeno[1,2-a]fluorene on bilayer NaCl/Au(111) a, DFTcalculated wave functions of the frontier orbitals of closed-shell 5 0 (isovalue: 0 002 e -Å -3 ) The wave functions shown here are calculated for the 5para geometry b, DFT-calculated bond lengths of 5ortho (top) and 5para (bottom) c, Constant-height I(V) spectra acquired on a species of 5 assigned as 5para, along with the corresponding dI/dV(V) spectra Open feedback parameters: V = -2 V, I = 0 15 pA (negative bias side) and V = 2 2 V, I = 0 15 pA (positive bias side) Acquisition position of the spectra is shown in Supplementary Fig  7  d, Scheme of many-body transitions associated to the measured ionic resonances of 5para Also shown are STM images of assigned 5para at biases where the corresponding transitions become accessible Scanning parameters: I = 0 15 pA (V = -1 5 V) and 0 2 pA (V = 1 7 V)  e, Laplace-filtered AFM image of assigned 5para STM set point: V = 0 2 V, I = 0 5 pA on bilayer NaCl, Δz = -0 7 Å  f, Selected bonds labeled for highlighting bond order differences between 5para and 5ortho For the bond pairs a/b, c/d and e/f, the bonds labeled in bold exhibit a higher bond order than their neighboring labeled bonds in 5para g, Laplace-filtered AFM images of 5 on bilayer NaCl/Cu(111) showing switching between 5OS and 5para as the molecule changes its adsorption position The faint protrusion adjacent to 5 is a defect that stabilizes the adsorption of 5  STM set point: V = 0 2 V, I = 0 5 pA on bilayer NaCl, Δz = -0 3Å  STM and STS data in c and d are acquired on the same species, while the AFM data in e is acquired on a different species Scale bars: 10 Å (d) and 5 Å (e,g) 
NMR (300 MHz, CDCl3) δ: 7 51 (m, 2H), 7 40 -7 28 (m, 5H), 7 27 -7 20 (m, 2H), 7 13 (d, J = 7 7 Hz, 1H), 2 07 (s, 3H), 1 77 (s, 3H) ppm  13C NMR-DEPT (75 MHz, CDCl3, 1:1 mixture of atropisomers) δ: 141 2 (C), 141 1 (C), 140 0 (C), 139 4 (2C), 137 5 (C), 137 4 (C), 136 0 (3C), 134 8 (C), 134 5 (C), 134 1 (C), 134 0 (C), 133 7 (C), 133 6 (C), 131 6 (CH), 131 2 (CH), 131 1 (CH), 130 7 (CH), 129 8 (CH), 129 7 (CH), 129 5 (CH), 129 4 (CH), 129 0 (CH), 128 9 (CH), 128 7 (2CH), 128 6 (2CH), 127 2 (CH), 127 1 (CH), 127 0 (CH), 126 9 (CH), 126 7 (CH), 126 6 (CH), 20 6 (CH3), 20 5 (CH3), 17 7 (CH3), 17 5 (CH3) ppm MS (APCI) m/z (%): 327 (M+1, 100) HRMS: C20H16Cl2; calculated: 327 0702, found: 327 0709 
NMR (500 MHz, CDCl3) δ: 7 93 (d, J = 7 6 Hz, 1H), 7 85 (d, J = 7 5 Hz, 1H), 7 78 (d, J = 7 7 Hz, 1H), 7 65 (d, J = 7 4 Hz, 1H), 7 61 (d, J = 7 5 Hz, 1H), 7 59 (d, J = 7 7 Hz, 1H), 7 47 (ddd, J = 8 4, 7 2, 1 1 Hz, 1H), 7 42 (dd, J = 8 1, 7 0 Hz, 1H), 7 35 (m, 2H), 4 22 (s, 3H), 4 02 (s, 3H) ppm  13C NMR-DEPT (125 MHz, CDCl3) δ: 144 1 (C), 143 3 (C), 142 3 (C), 141 9 (C), 141 8 (C), 141 2 (C), 138 2 (C), 136 5 (C), 127 0 (CH), 126 9 (CH), 126 7 (CH), 126 6 (CH), 125 3 (CH), 125 2 (CH), 123 6 (CH), 122 2 (CH), 119 9 (CH), 118 4 (CH), 37 4 (CH2), 36 3 (CH2) ppm MS (APCI) m/z (%): 254 (M+, 88) HRMS: C20H14; calculated: 254 1090, found: 254 1090 

abstract

Indenofluorenes are non-benzenoid conjugated hydrocarbons that have received great interest owing to their unusual electronic structure and potential applications in nonlinear optics and photovoltaics  Here, we report the generation of unsubstituted indeno[1,2-a]fluorene, the final and yet unreported parent indenofluorene regioisomer, on various surfaces by cleavage of two C-H bonds in 7,12-dihydro indeno[1,2-a]fluorene through voltage pulses applied by the tip of a combined scanning tunneling microscope and atomic force microscope 
On bilayer NaCl on Au(111), indeno[1,2a]fluorene is in the neutral charge state, while it exhibits charge bistability between neutral and anionic states on the lower work function surfaces of bilayer NaCl on Ag(111) and Cu(111)  In the neutral state, indeno[1,2-a]fluorene exhibits either of two ground states: an open-shell π-diradical state, predicted to be a triplet by density functional and multireference many-body perturbation theory calculations, or a closedshell state with a para-quinodimethane moiety in the as-indacene core 
Switching between open-and closed-shell states of a single molecule is observed by changing its adsorption site on NaCl  The inclusion of non-benzenoid carbocyclic rings is a viable route to tune the physicochemical properties of polycyclic conjugated hydrocarbons (PCHs)   Non-benzenoid polycycles may lead to local changes in strain, conjugation, aromaticity, and, relevant to the context of the present work, induce an open-shell ground state of the corresponding PCHs  
Many nonbenzenoid PCHs are also non-alternant, where the presence of odd-membered polycycles breaks the bipartite symmetry of the molecular network   Figure shows classical examples of non-benzenoid non-alternant PCHs, namely, pentalene, azulene and heptalene  Whereas azulene is a stable PCH exhibiting Hückel aromaticity ([4n+2] π-electrons, n = 2), pentalene and heptalene are unstable Hückel antiaromatic compounds with [4n] π-electrons, n = 2 (pentalene) and n = 3 (heptalene) 
Benzinterposition of pentalene generates indacenes, consisting of two isomers s-indacene and as-indacene (Fig  )  Apart from being antiaromatic, indacenes also contain proaromatic quinodimethane (QDM) moieties (Fig  ) , which endows them with potential open-shell character  While the parent s-indacene and asindacene have never been isolated, stable derivatives of s-indacene bearing bulky substituents have been synthesized  
A feasible strategy to isolate congeners of otherwise unstable non-benzenoid non-alternant PCHs is through fusion of benzenoid rings at the ends of the π-system, that is, benzannelation  For example, while the parent pentalene is unstable, the benzannelated congener indeno[2,1-a]indene is stable under ambient conditions (Fig  )  
However, the position of benzannelation is crucial for stability: although indeno[2,1a]indene is stable, its regioisomer indeno[1,2-a]indene (Fig  ) oxidizes under ambient conditions   Similarly, benzannelation of indacenes gives rise to the family of PCHs known as indenofluorenes (Fig  ), which constitute the topic of the present work 
Depending on the benzannelation position and the indacene core, five regioisomers can be constructed, namely, indeno [ Practical interest in indenofluorenes stems from their low frontier orbital gap and excellent electrochemical characteristics that render them as useful components in organic electronic devices  
The potential open-shell character of indenofluorenes has led to several theoretical studies on their use as non-linear optical materials and as candidates for singlet fission in organic photovoltaics   Recent theoretical work has also shown that indenofluorene-based ladder polymers may exhibit fractionalized excitations 
Fundamentally, indenofluorenes represent model systems to study the interplay between aromaticity and magnetism at the molecular scale   Motivated by many of these prospects, the last decade has witnessed intensive synthetic efforts toward the realization of indenofluorenes  Derivatives of 1-4 have been realized in solution , while 1-3 have also been synthesized on surfaces and characterized using scanning tunneling microscopy (STM) and atomic force microscopy (AFM), which provide information on molecular orbital densities , molecular structure and oxidation state  
With regards to the open-shell character of indenofluorenes, 2-4 are theoretically and experimentally interpreted to be closed-shell, while calculations indicate that 1 and 5 should exhibit open-shell ground states   Bulk characterization of mesitylsubstituted 1, including X-ray crystallography, temperature-dependent NMR, and electron spin resonance spectroscopy, provided indications of its open-shell ground state  
Electronic characterization of 1 on Au(111) surface using scanning tunneling spectroscopy (STS) revealed a low electronic gap of 0 4 eV (ref  )  However, no experimental proof of an openshell ground state of 1 on Au(111), such as detection of singly occupied molecular orbitals (SOMOs) or spin excitations and correlations due to unpaired electrons , was shown 
In this work, we report the generation and characterization of unsubstituted 5  Our research is motivated by theoretical calculations that indicate 5 to exhibit the largest diradical character among all indenofluorene isomers   The same calculations also predict that 5 should possess a triplet ground state 
Therefore, 5 would qualify as a Kekulé triplet, of which only a handful of examples exist   However, definitive synthesis of 5 has never been reported so far  Previously, Dressler et al  reported transient isolation of mesityl-substituted 5, where it decomposed both in the solution and in solid state , and only the structural proof of the corresponding dianion was obtained 
On-surface generation of a derivative of 5, starting from truxene as a precursor, was recently reported   STM data on this compound, containing the indeno[1,2-a]fluorene moiety as part of a larger PCH, was interpreted to indicate its open-shell ground state  However, the results did not imply the ground state of unsubstituted 5  Here, we show that on insulating surfaces 5 can exhibit either of two ground states: an open-shell or a closed-shell 
We infer the existence of these two ground states based on high-resolution AFM imaging with bond-order discrimination and STM imaging of molecular orbital densities   AFM imaging reveals molecules with two different geometries  Characteristic bond-order differences in the two geometries concur with the geometry of either an open-or a closed-shell state 
Concurrently, STM images at ionic resonances show molecular orbital densities corresponding to SOMOs for the open-shell geometry, but orbital densities of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) for the closed-shell geometry  Our experimental results are in good agreement with density functional theory (DFT) and multireference perturbation theory calculations 
Finally, we observe switching between open-and closed-shell states of a single molecule by changing its adsorption site on the surface  Synthetic strategy toward indeno[1,2-a]fluorene  The generation of 5 relies on the solution-phase synthesis of the precursor 7,12-dihydro indeno[1,2-a]fluorene (6)  Details on synthesis and characterization of 6 are reported in Supplementary Figs 
  Single molecules of 6 are deposited on coinage metal (Au(111), Ag(111) and Cu(111)) or insulator surfaces  In our work, insulating surfaces correspond to two monolayer-thick (denoted as bilayer) NaCl on coinage metal surfaces  Voltage pulses ranging between 4-6 V are applied by the tip of a combined STM/AFM system, which result in cleavage of one C-H bond at each of the pentagonal apices of 6, thereby leading to the generation of 5 (Fig  ) 
In the main text, we focus on the generation and characterization of 5 on insulating surfaces  Generation and characterization of 5 on coinage metal surfaces is shown in Supplementary Fig    )  Blue and orange colors represent spin up and spin down densities, respectively  c, Probability density of the SOMOs of 5OS (isovalue: 0 001 e -Å -3 ) 
d, DFT-calculated bond lengths of 5OS  e, Constant-height I(V) spectra acquired on a species of 5 assigned as 5OS, along with the corresponding dI/dV(V) spectra  Open feedback parameters: V = -2 V, I = 0 17 pA (negative bias side) and V = 2 V, I = 0 17 pA (positive bias side)  Acquisition position of the spectra is shown in Supplementary Fig    f, Scheme of many-body transitions associated to the measured ionic resonances of 5OS 
Also shown are STM images of assigned 5OS at biases where the corresponding transitions become accessible  Scanning parameters: I = 0 3 pA (V = -1 2 V and -1 5 V) and 0 2 pA (V = 1 3 V and 1 6 V)  g, Laplace-filtered AFM image of assigned 5OS  STM set point: V = 0 2 V, I = 0 5 pA on bilayer NaCl, Δz = -0 3
Å  The tip-height offset Δz for each panel is provided with respect to the STM setpoint, and positive (negative) values of Δz denote tip approach (retraction) from the STM setpoint  f and g show the same molecule at the same adsorption site, which is next to a trilayer NaCl island  The bright and dark features in the trilayer NaCl island in g correspond to Cl -and Na + ions, respectively 
Scale bars: 10 Å (f) and 5 Å (g)  To experimentally explore the electronic structure of 5, we used bilayer NaCl films on coinage metal surfaces to electronically decouple the molecule from the metal surfaces  Before presenting the experimental findings, we summarize the results of our theoretical calculations performed on 5 in the neutral charge state (denoted as 5 0 ) 
We start by performing DFT calculations on 5 0 in the gas phase  Geometry optimization performed at the spin-unrestricted UB3LYP/6-31G level of theory leads to one local minimum, 5OS, the geometry of which corresponds to the open-shell resonance structure of 5 (Fig  , the label OS denotes open-shell) 
The triplet electronic configuration of 5OS is the lowest-energy state, with the openshell singlet configuration 90 meV higher in energy  Geometry optimization performed at the restricted closed-shell RB3LYP/6-31G level reveals two local minima, 5para and 5ortho, the geometries of which (Fig  ) exhibit bond length alternations in line with the presence of a para-or an ortho-QDM moiety, respectively, in the as-indacene core of the closed-shell resonance structures of 5 (Fig  )  
Relative to 5OS in the triplet configuration, 5para and 5ortho are 0 40 and 0 43 eV higher in energy, respectively  Additional DFT results are shown in Supplementary Fig    To gain more accurate insights into the theoretical electronic structure of 5, we performed multireference perturbation theory calculations (Supplementary Fig  ) based on quasi-degenerate second-order n-electron valence state perturbation theory (QD-NEVPT2) 
In so far as the order of the ground and excited states are concerned, the results of QD-NEVPT2 calculations qualitatively match with DFT calculations  For 5OS, the triplet configuration remains the lowest-energy state, with the open-shell singlet configuration 60 meV higher in energy  The energy differences between the open-and closed-shell states are substantially reduced in QD-NEVPT2 calculations, with 5para and 5ortho only 0 11 and 0 21 eV higher in energy, respectively, compared to 5OS in the triplet configuration 
We also performed nucleus-independent chemical shift calculations to probe local aromaticity of 5 in the openand closed-shell states  While 5OS in the triplet configuration exhibits local aromaticity at the terminal benzenoid rings, 5OS in the open-shell singlet configuration, 5para and 5ortho all display antiaromaticity (Supplementary Fig  ) 
The choice of the insulating surface determines the charge state of 5: while 5 adopts neutral charge state on the high work function bilayer NaCl/Au(111) surface (irrespective of its openor closed-shell state, Supplementary Fig  ), 5 exhibits charge bistability between 5 0 and the anionic state 5 -1 on the lower work function bilayer NaCl/Ag(111) and Cu(111) surfaces (Supplementary Figs  ) 
In the main text, we focus on the characterization of 5 on bilayer NaCl/Au(111)  Characterization of charge bistable 5 is reported in Supplementary Figs    We first describe experiments on 5 on bilayer NaCl/Au(111), where 5 exhibits a geometry corresponding to the calculated 5OS geometry, and an open-shell electronic configuration 
We compare the experimental data on this species to calculations on 5OS with a triplet configuration, as theory predicts a triplet ground state for 5OS  For 5OS, the calculated frontier orbitals correspond to the SOMOs ψ1 and ψ2 (Fig  ), whose spin up levels are occupied and the spin down levels are empty 
Figure shows the DFT-calculated bond lengths of 5OS, where the two salient features, namely, the small difference in the bond lengths within each ring and the notably longer bond lengths in the pentagonal rings, agree with the open-shell resonance structure of 5 (Fig  )  Figure shows an AFM image of 5 adsorbed on bilayer NaCl/Au(111) that we assign as 5OS, where the bond-order differences qualitatively correspond to the calculated 5OS geometry (discussed and compared to the closed-shell state below) 
Differential conductance spectra (dI/dV(V), where I and V denote the tunneling current and bias voltage, respectively) acquired on assigned 5OS exhibit two peaks centered at -1 5 V and 1 6 V (Fig  ), which we assign to the positive and negative ion resonances (PIR and NIR), respectively  Figure shows the corresponding STM images acquired at the onset (V = -1 2
V/1 3 V) and the peak (V = -1 5 V/1 6 V) of the ionic resonances  To draw a correspondence between the STM images and the molecular orbital densities, we consider tunneling events as many-body electronic transitions between different charge states of 5OS (Fig  )  Within this framework, the PIR corresponds to transitions between 5 0 and the cationic state 5  
At the onset of the PIR at -1 2 V, an electron can only be detached from the SOMO ψ1 and the corresponding STM image at -1 2 V shows the orbital density of ψ1  Increasing the bias to the peak of the PIR at -1 5 V, it becomes possible to also empty the SOMO ψ2, such that the corresponding STM image shows the superposition of ψ1 and ψ2, that is, |ψ1| 2 + |ψ2| 2 (ref 
)  Similarly, the NIR corresponds to transitions between 5 0 and 5 -1   At the NIR onset of 1 3 V, only electron attachment to ψ2 is energetically possible  At 1 6 V, electron attachment to ψ1 also becomes possible, and the corresponding STM image shows the superposition of ψ1 and ψ2  The observation of the orbital densities of SOMOs, and not the hybridized HOMO and LUMO, proves the open-shell ground state of assigned 5OS 
Measurements of the monoradical species with a doublet ground state are shown in Supplementary Fig    Unexpectedly, another species of 5 was also experimentally observed that exhibited a closedshell ground state  In contrast to 5OS, where the frontier orbitals correspond to the SOMOs ψ1 and ψ2, DFT calculations predict orbitals of different shapes and symmetries for 5para and 5ortho, denoted as α and β and shown in Fig   
For 5ortho, α and β correspond to HOMO and LUMO, respectively  The orbitals are inverted in energy and occupation for 5para, where β is the HOMO and α is the LUMO  Fig  shows an AFM image of 5 that we assign as 5para  We experimentally infer its closed-shell state first by using qualitative bond order discrimination by AFM 
In high-resolution AFM imaging, chemical bonds with higher bond order are imaged brighter (that is, with higher frequency shift Δf) due to stronger repulsive forces, and they appear shorter   In Fig  , we label seven bonds whose bond orders show significant qualitative differences in the calculated 5ortho, 5para (Fig  ) and 5OS (Fig  ) geometries 
In 5para, the bonds b and d exhibit a higher bond order than a and c, respectively  This pattern is reversed for 5ortho, while the bond orders of the bonds a-d are all similar and small for 5OS  Furthermore, in 5para bond f exhibits a higher bond order than e, while in 5ortho and 5OS bonds e and f exhibit similar bond order (because they belong to Clar sextets) 
Finally, the bond labeled g shows a higher bond order in 5para than in 5ortho and 5OS  The AFM image of assigned 5para shown in Fig  indicates higher bond orders of the bonds b, d and f compared to a, c and e, respectively  In addition, the bond g appears almost point-like and with enhanced Δf contrast compared to its neighboring bonds, indicative of a high bond order (see Supplementary Fig  for height-dependent measurements) 
These observations concur with the calculated 5para geometry (Fig  )  Importantly, all these distinguishing bond-order differences are distinctly different in the AFM image of 5OS shown in Fig  , which is consistent with the calculated 5OS geometry (Fig  )  In the AFM images of 5OS (Fig  and Supplementary Fig  ), the bonds a-d at the pentagon apices appear with similar contrast and apparent bond length 
The bonds e and f at one of the terminal benzenoid rings also exhibit similar contrast and apparent bond length, while the central bond g appears longer compared to assigned 5para  Further compelling evidence for the closed-shell state of assigned 5para is obtained by STM and STS  dI/dV(V) spectra acquired on an assigned 5para species exhibit two peaks centered at -1 4 V (PIR) and 1 6 V (NIR) (Fig  ) 
STM images acquired at these biases (Fig  ) show the orbital densities of β (-1 4 V) and α (1 6 V)  First, the observation of α and β as the frontier orbitals of this species, and not the SOMOs, strongly indicates its closed-shell state  Second, consistent with AFM measurements that indicate good correspondence to the calculated 5para geometry, we observe β as the HOMO and α as the LUMO 
For 5ortho, α should be observed as the HOMO and β as the LUMO  We did not observe molecules with the signatures of 5ortho in our experiments  We observed molecules in open-(5OS, Fig  ) and closed-shell (5para, Fig  ) states in similar occurrence after their generation from 6 on the surface  We could also switch individual molecules between open-and closed-shell states as shown in Fig  and Supplementary Fig   
To this end, a change in the adsorption site of a molecule was induced by STM imaging at ionic resonances, which often resulted in movement of the molecule  The example presented in Fig  shows a molecule that was switched from 5para to 5OS and back to 5para  The switching is not directed, that is, we cannot choose which of the two species will be formed when changing the adsorption site, and we observed 5OS and 5para in approximately equal yields upon changing the adsorption site 
The molecule in Fig  is adsorbed on top of a defect that stabilizes its adsorption geometry on bilayer NaCl  At defect-free adsorption sites on bilayer NaCl, that is, without a third layer NaCl island or atomic defects in the vicinity of the molecule, 5 could be stably imaged neither by AFM nor by STM at ionic resonances (Supplementary Fig  ) 
Without changing the adsorption site, the state of 5 (open-or closedshell) never changed, including the experiments on bilayer NaCl/Ag(111) and Cu(111), on which the charge state of 5 could be switched (Supplementary Figs  )  Also on these lower work function surfaces, both open-and closed-shell species were observed for 5 0 and both showed charge bistability between 5 0 (5OS or 5para) and 5 -1 (Supplementary Figs  ) 
The geometrical structure of 5 -1 probed by AFM, and its electronic structure probed by STM imaging at the NIR (corresponding to transitions between 5 -1 and the dianionic state 5 -2 ), are identical within the measurement accuracy for the charged species of both 5OS and 5para  When cycling the charge state of 5 between 5 0 and 5 -1 several times, we always observed the same state (5OS or 5para) when returning to 5 0 , provided the molecule did not move during the charging/discharging process 
Based on our experimental observations we conclude that indeno[1,2-a]fluorene (5), the last unknown indenofluorene isomer, can be stabilized in and switched between an open-shell (5OS) and a closed-shell (5para) state on NaCl  For the former, both DFT and QD-NEVPT2 calculations predict a triplet electronic configuration 
Therefore, 5 can be considered to exhibit the spin-crossover effect, involving magnetic switching between high-spin (5OS) and low-spin (5para) states, coupled with a reversible structural transformation  So far, the spin-crossover effect has mainly only been observed in transition-metal-based coordination compounds with a near-octahedral geometry  
The observation that the switching between open-and closedshell states is related to changes in the adsorption site but is not achieved by charge-state cycling alone, indicates that the NaCl surface and local defects facilitate different electronic configurations of 5 depending on the adsorption site 
Gas-phase QD-NEVPT2 calculations predict that 5OS is the ground state, and the closed-shell 5para and 5ortho states are 0 11 and 0 21 eV higher in energy  The experiments, showing bidirectional switching between 5OS and 5para, indicate that a change in the adsorption site can induce sufficient change in the geometry of 5 (leading to a corresponding change in the ground state electronic configuration) and thus induce switching 
Switching between open-and closed-shell states in 5 does not require the breaking or formation of covalent bonds , but a change of adsorption site on NaCl where the molecule is physisorbed  Our results should have implications for single-molecule devices, capitalizing on the altered electronic and chemical properties of a system in π-diradical open-shell and closed-shell states such as frontier orbital and singlet-triplet gaps, and chemical reactivity 
For possible future applications as a single-molecule switch, it might be possible to also switch between open-and closed-shell states by changing the local electric field, such as by using chargeable adsorbates   Scanning probe microscopy measurements and sample preparation  STM and AFM measurements were performed in a home-built system operating at base pressures below 1×10 -10 mbar and a base temperature of 5 K  Bias voltages are provided with respect to the sample 
All STM, AFM and spectroscopy measurements were performed with carbon monoxide (CO) functionalized tips  AFM measurements were performed in non-contact mode with a qPlus sensor   The sensor was operated in frequency modulation mode with a constant oscillation amplitude of 0 5 Å  STM measurements were performed in constantcurrent mode, AFM measurements were performed in constant-height mode with V = 0 V, and I(V) and Δf(V) spectra were acquired in constant-height mode 
Positive (negative) values of the tip-height offset Δz represent tip approach (retraction) from the STM setpoint  All dI/dV(V) spectra are obtained by numerical differentiation of the corresponding I(V) spectra  STM and AFM images, and spectroscopy curves, were post-processed using Gaussian low-pass filters 
Au(111), Ag(111) and Cu(111) surfaces were cleaned by iterative cycles of sputtering with Ne + ions and annealing up to 800 K  NaCl was thermally evaporated on Au(111), Ag(111) and Cu(111) surfaces held at 323 K, 303 K and 283 K, respectively  This protocol results in the growth of predominantly bilayer (100)-terminated islands, with a minority of trilayer islands 
Sub-monolayer coverage of 6 on surfaces was obtained by flashing an oxidized silicon wafer containing the precursor molecules in front of the cold sample in the microscope  CO molecules for tip functionalization were dosed from the gas phase on the cold sample  Density functional theory calculations  DFT was employed using the PSI4 program package  
All molecules with different charge (neutral and anionic) and electronic (open-and closed-shell) states were independently investigated in the gas phase  The B3LYP exchangecorrelation functional with 6-31G basis set was employed for structural relaxation and singlepoint energy calculations  The convergence criteria were set to 10 −4 eV Å −1 for the total forces and 10 −6 eV for the total energies 
Multireference calculations  Multireference calculations were performed on the DFToptimized geometries using the QD-NEVPT2 level of theory , with three singlet roots and one triplet root included in the state-averaged calculation  A (10,10) active space (that is, 10 electrons in 10 orbitals) was used along with the def2-TZVP basis set  
Increasing either the active space size or expanding the basis set resulted in changes of about 50 meV for relative energies of the singlet and triplet states  These calculations were performed using the ORCA program package   Nucleus-independent chemical shift (NICS) calculations  Isotropic nucleus-independent chemical shift values were evaluated at the centre of each ring using the B3LYP exchangecorrelation functional with def2-TZVP basis set using the Gaussian 16 software package  
Starting materials (reagent grade) were purchased from TCI and Sigma-Aldrich and used without further purification  Reactions were carried out in flame-dried glassware and under an inert atmosphere of purified Ar using Schlenk techniques  Thin-layer chromatography (TLC) was performed on Silica Gel 60 F-254 plates (Merck) 
Column chromatography was performed on silica gel (40-60 µm)  Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Varian Mercury 300 or Bruker Varian Inova 500 spectrometers  Mass spectrometry (MS) data were recorded in a Bruker Micro-TOF spectrometer  The synthesis of compound 6 was developed following the two-step synthetic route shown in Supplementary Fig  , which is based on the preparation of methylene-bridge polyarenes by means of Pd-catalyzed activation of benzylic C-H bonds  
Supplementary Figure | Synthetic route to obtain compound 6  The complex Pd2(dba)3 (20 mg, 0 02 mmol) was added over a deoxygenated mixture of 1,3-dibromo-2,4-dimethylbenzene (9, 100 mg, 0 38 mmol), boronic acid 10 (178 mg, 1 14 mmol), K2CO3 (314 mg, 2 28 mmol) and XPhos (35 mg, 0 08 mmol) in toluene (1:1, 10 mL), and the resulting mixture was heated at 90 °C for 2 h 
After cooling to room temperature, the solvents were evaporated under reduced pressure  The reaction crude was purified by column chromatography (SiO2; hexane:CH2Cl2 9:1) affording 11 (94 mg, 76%) as a colorless oil  The complex Pd(OAc)2 (7 mg, 0 03 mmol) was added over a deoxygenated mixture of terphenyl 11 (90 mg, 0 27 mmol), K2CO3 (114 mg, 0 83 mmol) and ligand L (26 mg, 0 06 mmol) in NMP (2 mL) 
The resulting mixture was heated at 160 °C for 4 h  After cooling to room temperature, H2O (30 mL) was added, and the mixture was extracted with EtOAc (3x15 mL)  The combined organic extracts were dried over anhydrous Na2SO4, filtered, and evaporated under reduced pressure  The reaction crude was purified by column chromatography (SiO2; hexane:CH2Cl2 9:1) affording compound 6 (8 mg, 11%) as a white solid  in AFM imaging due to their reduced adsorption height compared to the rest of the carbon atoms 
We attribute this observation to the significantly different lattice parameter of Cu(111) (2 57 Å) compared to Au(111) and Ag(111) (2 95 Å and 2 94 Å, respectively) , such that the apical carbon atoms of the pentagonal rings of 5 adsorb on the on-top atomic sites on Au(111) and Ag(111), but not on Cu(111) 
Our speculation is based on a previous study of polymers of 1 on Au(111) by Di Giovannantonio et al  , where both tilted and planar individual units of 1 were observed depending on whether the apical carbon atoms of the pentagonal rings in 1 adsorbed on the on-top or hollow sites of the surface, respectively 
Given the strong molecule-metal interaction, we found no electronic state signatures of 5 on all three metal surfaces  STM set point for AFM images: V = 0  e, Frontier orbital spectrum of 5 -1   In the anionic state, ψ2 becomes doubly occupied and ψ1 is the SOMO  Filled and empty circles denote occupied and empty orbitals, respectively 
For each panel, zero of the energy axis has been aligned to the respective highest-energy occupied orbital 
Context 3: Outdoors	February 19, 2017
You are here: Home / Archives for Departments / OutdoorsActor Sam Waterson Hosts PBS Documentary on Lyme Land Trust January 14, 2017 by admin Leave a Comment Jack Tiffany, owner of Tiffany Farms on Rte  156 and an earlier pioneer in Lyme land preservation, is interviewed by PBS “Visionaries” documentary producers 
Filed Under: Lyme, Outdoors Application Deadline for Environmental Leadership Scholarship is Feb  1 January 8, 2017 by admin Leave a Comment Applications are now being accepted for the Virginia R  Rollefson Environmental Leadership Scholarship, a $1,000 award to recognize a high school student who has demonstrated leadership and initiative in promoting conservation, preservation, restoration, or environmental education 
Filed Under: Lyme, News, Old Lyme, Outdoors, Top Story Preserves in Lyme Now Closed for Hunting During Weekdays November 17, 2016 by admin Leave a Comment Starting yesterday, Wednesday, Nov  16, the following Preserves in Lyme will be closed Monday through Friday until Tuesday, Dec  20, 2016, except to licensed hunters with valid consent forms from the Town of Lyme Open Space Coordinator:
Banningwood Preserve
Beebe Preserve
Chestnut Hill Preserve
Eno Preserve
Hand Smith
Honey Hill Preserve
Jewett Preserve
Mount Archer Woods
Pickwick’s Preserve
Plimpton Preserve
Slawson Preserve
These preserves, owned by the Town of Lyme or the Lyme Land Conservation Trust, will be open on Saturdays and Sundays during this hunting period as no hunting is allowed on weekends 
The hunting program is fully subscribed 
For more information on the hunting program in Lyme, visit http://www lymelandtrust org/stewardship/hunting-program/
Filed Under: Lyme, Outdoors, Top Story Town of Old Lyme Offers Part-time Land Steward Opportunity October 11, 2016 by admin Leave a Comment The Town of Old Lyme is seeking a part-time individual to maintain and manage the trail systems on its major preserves  Keeping trails cleared, maintaining markers, kiosks, entrances, parking areas, and managing for wildlife and other natural resources are the priorities 
For more information, visit the job posting on the home page of the Town’s web page at http://www oldlyme-ct gov/Pages/index 
To learn about the Open Space Commission and the properties it manages, visit http://www oldlyme-ct gov/Pages/OldLymeCT_Bcomm/open_space
Filed Under: Old Lyme, Outdoors, Top Story CT Fund for the Environment Annual Meeting to be Held Sunday in Hartford September 22, 2016 by admin Leave a Comment Engaging and educating communities for preservation of the Long Island Sound tidal estuary
Save the Sound is celebrating National Estuaries Week Sept  17 – 24 with a series of interactive and educational events throughout the Long Island Sound region  This annual celebration of estuaries—the vital coastal zones where freshwater rivers meet salty seas—is sponsored by Restore America’s Estuaries and its member organizations including Save the Sound  This year’s events call attention to the many benefits of thriving coastal ecosystems, including how estuary conservation efforts support our quality of life and economic well-being 
“The Long Island Sound estuary is not only where freshwater rivers meet the saltwater Atlantic, but where wildlife habitat meets beaches and boating, and where modern industry meets traditional oystering,” said Curt Johnson, executive director of Save the Sound, which is a bi-state program of Connecticut Fund for the Environment (CFE) 
Johnson continued, “All over the country, estuaries are the lifeblood of coastal economies  From serving as natural buffers to protect our coastlines from storms to providing unique habitat for countless birds, fish, and wildlife, estuaries deserve our protection and our thanks ”
Save the Sound is celebrating estuaries with a number of events this week, including the release of a new video, a presentation on Plum Island at the Old Lyme-Phoebe Griffin Noyes Library and the CFE/Save the Sound annual meeting:
Aerial view of Plum Island lighthouse  (From Preserve Plum Island website)
Chris Cryder, Special Projects Coordinator for Save the Sound and Outreach Coordinator for the Preserve Plum Island Coalition, will host Preserving Plum Island for Future Generations, a special presentation on the importance of conserving the wildlife habitats and historic buildings of Plum Island, New York 
Plum Island flanks Plum Gut in the Long Island Sound estuary’s eastern end, where fast-moving tides create highly productive fishing grounds  The talk is part of a multi-week series featuring photographs and paintings of Plum Island, and lectures on its ecology, geology, and history 
Old Lyme-Phoebe Griffin Noyes Library, 2 Library Lane, Old Lyme, Connecticut
Register by calling the library at 860-434-1684 
The Annual Meeting of Connecticut Fund for the Environment and its bi-state program Save the Sound will take place in the Planet Earth exhibit at the Connecticut Science Center  The event is open to the public with registration, and will feature a keynote address from Curt Spalding, administrator of EPA’s New England Region  Spalding is a leader in combatting nitrogen pollution and in climate change resilience planning efforts for New England 
Connecticut Science Center, 250 Columbus Blvd, Hartford, Connecticut
4 – 7 p m
RSVP to mlemere@ctenvironment org
To celebrate the contributions of volunteers to restoring the Long Island Sound estuary, Save the Sound has released a new video of a habitat restoration planting at Hyde Pond in Mystic  Following removal of the old Hyde Pond dam and opening 4 1 miles of stream habitat for migratory fish last winter (see time lapse video here), in May about 30 volunteers planted native vegetation along the Whitford Brook stream bank, under the direction of U S  Fish and Wildlife Service, CT DEEP’s Fisheries division, and Save the Sound staff 
Find more information on the project’s benefits and funders here 
Look for the planting video on Save the Sound’s website, YouTube, Facebook, and Twitter accounts 
Filed Under: Old Lyme, Outdoors 750+ Volunteers Clean Beaches from Norwalk to New London Including Griswold Point in Old Lyme September 17, 2016 by admin Leave a Comment Kendall Perkins displays a skull she found during Save The Sound‘s Coastal Clean-up Day held yesterday at White Sand Beach 
Save the Sound, a bi-state program of Connecticut Fund for the environment, organized 31 cleanups across Connecticut’s shoreline this weekend  The efforts are part of International Coastal Cleanup, which brings together hundreds of thousands of people each year to remove plastic bags, broken glass, cigarette butts, and other trash from the world’s shores and waterways  One of the areas included in the cleanup effort was from White Sand Beach to the tip of Griswold Point in Old Lyme 
The event was founded by Ocean Conservancy in 1985, and Save the Sound has served as the official Connecticut coordinator for the last 14 years 
“We didn’t plan it this way, but I can’t imagine a better way to celebrate the 31st anniversary of International Coastal Cleanup Day than with 31 cleanups!” said Chris Cryder, special projects coordinator for Save the Sound  “The cleanup just keeps growing, in Connecticut and worldwide  We have some terrific new and returning partners this year, including the SECONN Divers, folks from the U S  District Court, multiple National Charity League chapters, and many more ”
Cryder continued, “The diversity of the groups involved really reflects the truth that ocean health affects all of us  Clean beaches and oceans are safer for beachgoers and boaters, they’re healthier for wildlife that aren’t eating plastic or getting tangled up in trash, and they’re economic powerhouses for the fishing and tourism industries ”
The cleanups are co-hosted by a wide array of local partners including high schools, youth groups, and scout troops; churches; boaters and divers; watershed associations, park stewards, and land trusts  Twenty-eight cleanups will be held Saturday, with three more on Sunday and others through mid-October, for a total of 70 cleanups statewide 
Based on the estimates of cleanup captains, between 750 and 900 volunteers were expected to pitch in on Saturday alone  Last year, a total of 1,512 volunteers participated in Save the Sound cleanups throughout the fall  They collected more than three tons of litter and debris from 58 sites on Connecticut beaches, marshes, and riverbanks 
Over the event’s three-decade history, 11 5 million volunteers have collected 210 million pounds of trash worldwide  Every piece of trash volunteers find is tracked, reported to Save the Sound, and included in Ocean Conservancy’s annual index of global marine debris  The data is used to track trends in litter and devise policies to stop it at its source 
Filed Under: Old Lyme, Outdoors, Top Story Stonewell Farm Hosts Two-Day Workshop on Dry Stone Wall Building, Sept  24, 25 September 13, 2016 by admin Leave a Comment Andrew Pighill’s work includes outdoor kitchens, wine cellars, fire-pits, fireplaces and garden features that include follies and other whimsical structures in stone 
KILLINGWORTH — On Sept  24 and 25, from 9 a m  to 4 p m  daily, Andrew Pighills, master stone mason, will teach a two-day, weekend long workshop on the art of dry stone wall building at Stonewell Farm in Killingworth, CT 
Participants will learn the basic principles of wall building, from establishing foundations, to the methods of dry laid (sometimes called dry-stacked) construction and ‘hearting’ the wall  This hands-on workshop will address not only the structure and principles behind wall building but also the aesthetic considerations of balance and proportion 
This workshop expresses Pighill’s commitment to preserve New England’s heritage and promote and cultivate the dry stone wall building skills that will ensure the preservation of our vernacular landscape 
This workshop is open to participants, 18 years of age or older, of all levels of experience  Note the workshop is limited to 16 participants, and spaces fill up quickly 
You must pre-register to attend the workshop  The price for the workshop is $350 per person  Stonewell Farm is located at 39 Beckwith Rd , Killingworth CT 06419
If you have any questions or to register for the workshop, contact the Workshop Administrator Michelle Becker at 860-322-0060 or mb@mbeckerco com
At the end of the day on Saturday you’ll be hungry, tired and ready for some rest and relaxation, so the wood-fired Stone pizza oven will be fired up and beer, wine and Pizza Rustica will be served 
About the instructor: Born in Yorkshire, England, Andrew Pighills is an accomplished stone artisan, gardener and horticulturist  He received his formal horticulture training with The Royal Horticultural Society and has spent 40+ years creating gardens and building dry stone walls in his native England in and around the spectacular Yorkshire Dales and the English Lake District  Today, Pighills is one of a small, but dedicated group of US-based, certified, professional members of The Dry Stone Walling Association (DSWA) of Great Britain  Having moved to the United States more than 10 years ago, he now continues this venerable craft here in the US, building dry stone walls, stone structures and creating gardens throughout New England and beyond 
His particular technique of building walls adheres to the ancient methods of generations of dry stone wallers in his native Yorkshire Dales  Pighills’ commitment to preserving the integrity and endurance of this traditional building art has earned him a devoted list of private and public clients here and abroad including the English National Trust, the English National Parks, and the Duke of Devonshire estates  His stone work has been featured on British and American television, in Charles McCraven’s book The Stone Primer, and Jeffrey Matz’s Midcentury Houses Today, A study of residential modernism in New Canaan Connecticut  He has featured in the N Y Times, on Martha Stewart Living radio, and in the Graham Deneen film short “Dry Stone”, as well as various media outlets both here and in the UK, including an article in the Jan/Feb 2015 issue of Yankee Magazine 
Pighills is a DSWA fully qualified dry stone walling instructor  In addition to building in stone and creating gardens, Pighills teaches dry stone wall building workshops in and around New England  He is a frequent lecturer on the art of dry stone walling, and how traditional UK walling styles compare to those found in New England  His blog, Heave and Hoe; A Day in the Life of a Dry Stone Waller and Gardener, provides more information about Pighills 
For more information, visit www englishgardensandlandscaping com
Filed Under: Outdoors CT Port Authority Chair Tells Lower CT River Local Officials, “We’re All on One Team” August 27, 2016 by Olwen Logan 2 Comments Enjoying a boat ride on the Connecticut River, but still finding time for discussions, are (from left to right) Chester First Selectwoman Lauren Gister, Old Lyme First Selectwoman and Connecticut Port Authority (CPA) board member Bonnie Reemsnyder, Essex First Selectman Norm Needleman, CPA Chairman Scott Bates and Deep River First Selectman Angus McDonald, Jr 
Filed Under: Chester, Deep River, Essex, News, Old Lyme, Outdoors, Politics, Top Story House Approves Courtney-Sponsored Amendment Restricting Sale of Plum Island July 10, 2016 by admin 2 Comments Representative Joe Courtney
Local Congressional Representative Joe Courtney (CT-02) announced Thursday (July 7) that a bipartisan amendment he had led, along with Representatives Rosa DeLauro (CT-03), Lee Zeldin (R-NY) and Peter King (R-NY), to prohibit the sale of Plum Island was passed by the House of Representatives 
The amendment, which will prohibit the General Services Administration (GSA) from using any of its operational funding to process or complete a sale of Plum Island, was made to the Financial Services and General Government Appropriations Act of 2017  
In a joint statement, the Representatives said, “Our amendment passed today is a big step toward permanently protecting Plum Island as a natural area  Plum Island is a scenic and biological treasure located right in the middle of Long Island Sound  It is home to a rich assortment of rare plant and animal species that need to be walled off from human interference ”
The statement continued, “Nearly everyone involved in this issue agrees that it should be preserved as a natural sanctuary – not sold off to the highest bidder for development ” Presumptive Republican Presidential nominee Donald Trump had shown interest in the property at one time 
In 2008, the federal government announced plans to close the research facility on Plum Island and relocate to Manhattan, Kansas  Current law states that Plum Island must be sold publicly to help finance the new research facility 
Aerial view of Plum Island 
The lawmakers joint statement explained, “The amendment will prevent the federal agency in charge of the island from moving forward with a sale by prohibiting it from using any of its operational funding provided by Congress for that purpose,” concluding, ” This will not be the end of the fight to preserve Plum Island, but this will provide us with more time to find a permanent solution for protecting the Island for generations to come



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For several years, members from both sides of Long Island Sound have been working in a bipartisan manner to delay and, ultimately, repeal the mandated sale of this ecological treasure  Earlier this year, the representatives, along with the whole Connecticut delegation, cosponsored legislation that passed the House unanimously to delay the sale of Plum Island 
Filed Under: Outdoors July 1 Update: Aquatic Treatment Planned for Rogers Lake, July 5 July 1, 2016 by admin Leave a Comment We received this updated information from the Old Lyme Selectman’s office at 11:05 a m  this morning:
Filed Under: Lyme, Old Lyme, Outdoors, Town Hall They’re Everywhere! All About Gypsy Moth Caterpillars — Advice from CT Agricultural Experiment Station June 2, 2016 by Adina Ripin Leave a Comment Gypsy moth caterpillars – photo by Peter Trenchard, CAES 
The potential for gypsy moth outbreak exists every year in our community 
Dr  Kirby Stafford III, head of the Department of Entomology at the Connecticut Agricultural Experiment Station, has written a fact sheet on the gypsy moth available on the CAES website  The following information is from this fact sheet 
The gypsy moth, Lymantria dispar, was introduced into the US (Massachusetts) by Etienne Leopold Trouvelot in about 1860  The escaped larvae led to small outbreaks in the area in 1882, increasing rapidly  It was first detected in Connecticut in 1905  By 1952, it had spread to 169 towns  In 1981, 1 5 million acres were defoliated in Connecticut  During the outbreak of 1989, CAES scientists discovered that an entomopathogenic fungus, Entomophaga maimaiga, was killing the caterpillars  Since then the fungus has been the most important agent suppressing gypsy moth activity 
The fungus, however, cannot prevent all outbreaks and hotspots have been reported in some areas, in 2005-06 and again in 2015 
The life cycle of the gypsy moth is one generation a year  Caterpillars hatch from buff-colored egg masses in late April to early May  An egg mass may contain 100 to more than 1000 eggs and are laid in several layers  The caterpillars (larvae) hatch a few days later and ascend the host trees and begin to feed on new leaves  The young caterpillars, buff to black-colored, lay down silk safety lines as they crawl and, as they drop from branches on these threads, they may be picked up on the wind and spread 
There are four or five larval stages (instars) each lasting 4-10 days  Instars 1-3 remain in the trees  The fourth instar caterpillars, with distinctive double rows of blue and red spots, crawl up and down the tree trunks feeding mainly at night  They seek cool, shaded protective sites during the day, often on the ground  If the outbreak is dense, caterpillars may feed continuously and crawl at any time 
With the feeding completed late June to early July, caterpillars seek a protected place to pupate and transform into a moth in about 10-14 days  Male moths are brown and fly  Female moths are white and cannot fly despite having wings  They do not feed and live for only 6-10 days  After mating, the female will lay a single egg mass and die  The egg masses can be laid anywhere: trees, fence posts, brick/rock walls, outdoor furniture, cars, recreational vehicles, firewood  The egg masses are hard  The eggs will survive the winter and larvae hatch the following spring during late April through early May 
The impact of the gypsy moth can be extensive since the caterpillar will feed on a wide diversity of trees and shrubs  Oak trees are their preferred food  Other favored tree species include apple, birch, poplar and willow  If the infestation is heavy, they will also attack certain conifers and other less favored species  The feeding causes extensive defoliation 
Healthy trees can generally withstand one or two partial to one complete defoliation  Trees will regrow leaves before the end of the summer  Nonetheless, there can be die-back of branches  Older trees may become more vulnerable to stress after defoliation  Weakened trees can also be attacked by other organisms or lack energy reserves for winter dormancy and growth during the following spring  Three years of heavy defoliation may result in high oak mortality 
The gypsy moth caterpillars drop leaf fragments and frass (droppings) while feeding creating a mess for decks, patios, outdoor furniture, cars and driveways  Crawling caterpillars can be a nuisance and their hairs irritating  The egg masses can be transported by vehicles to areas where the moth is not yet established  Under state quarantine laws, the CAES inspects certain plant shipments destined to areas free of the gypsy moth, particularly for egg masses 
There are several ways to manage the gypsy moth: biological, physical and chemical 
Biologically, the major gypsy moth control agent has been the fungus E  maimaiga  This fungus can provide complete control of the gypsy moth but is dependent on early season moisture from rains in May and June to achieve effective infection rates and propagation of the fungus to other caterpillars  The dry spring of 2015 resulted in little or no apparent fungal inoculation or spread until it killed late-stage caterpillars in some areas of the state, after most defoliation 
Infected caterpillars hang vertically from the tree trunk, head down  Some die in an upside down “V” position, a characteristic of caterpillars killed by the less common gypsy moth nucleopolyhedrosis virus (NPV)  This was not detected in caterpillars examined in 2015 
Physical controls include removing and destroying egg masses, which can be drowned in a soapy water and disposed of  Another method is to use burlap refuge/barrier bands wrapped around tree trunks so that migrating caterpillars will crawl into or under the folded burlap or be trapped by the sticky band 
There are a number of crop protection chemicals labeled for the control of gypsy moth on ornamental trees and shrubs  There are treatments for egg masses, larvae and adult moths  Detailed information about these chemical treatments is available in the CAES factsheet 
For complete information about the gypsy moth and its management, visit the CAES website and look for the fact sheet on gypsy moth 
Filed Under: News, Outdoors East Lyme Public Trust Invites Community to Celebrate Boardwalk Re-dedication May 25, 2016 by admin Leave a Comment On Saturday, May 28, at 11 a m , the East Lyme Public Trust Foundation, in co-operation with East Lyme Parks and Recreation Department, will sponsor A Dream Fulfilled, the official re-dedication of the East Lyme Boardwalk  The re-dedication ceremony, which will be held on the Boardwalk, will feature keynote speaker, Sen  Paul Formica, former First Selectman of East Lyme 
Other speakers will include East Lyme First Selectman Mark Nickerson, Public Trust President Joe Legg, Public Trust Past-President Bob DeSanto, Public Trust Vice-President John Hoye, and Parks and Recreation Director Dave Putnam; all the speakers will recognize the many people who have helped made this dream a reality 
The East Lyme Public Trust Foundation would like to invite the general public to witness this historic occasion  In addition, the members would especially like to encourage the participation of the 200 people who dedicated benches and the innumerable people who sponsored plaques  They would also love to welcome all members of the Trust – past and present – and all those who originally helped make the Boardwalk a reality 
Participants should enter the Boardwalk at Hole-in-the Wall on Baptist Lane, Niantic  Then, there will be a short walk to the area of the monument where the ceremony will take place  At the entrance to Hole-in-the Wall, the Public Trust will have a display of historical information and memorabilia related to the construction and re-construction of the Boardwalk  Public Trust members, Pat and Jack Lewis will be on hand to host the exhibit titled Before and After and to welcome participants  After the ceremony, participants will have the opportunity to visit “their bench” and re-visit “their plaque ” During and after the dedication, music will be provided by Trust member, Bill Rinoski, who is a “D J  for all occasions ” Rinoski will feature “Boardwalk-related” music and Oldies plus Top 40 selections  This historic occasion will be videotaped as a public service by Mike Rydene of Media Potions of East Lyme  High school volunteers will be on hand to greet participants and help with directions 
The organizing committee is chaired by Michelle Maitland  Her committee consists of Joe Legg, President of the East Lyme Public Trust, Carol Marelli, Bob and Polly DeSanto, June Hoye, and Kathie Cassidy 
Visit Facebook – East Lyme Public Trust Foundation – for more information on the re-dedication ceremony  For more information on the Boardwalk, explore this website 
Filed Under: Outdoors Lyme Land Trust Seeks to Preserve Whalebone Cove Headwaters May 8, 2016 by admin Leave a Comment Lyme Land Trust Preservation Vice President Don Gerber stands with Chairman Anthony Irving (kneeling) next to Whalebone Creek in the proposed Hawthorne Preserve in Hadlyme 
The Lyme Land Conservation Trust has announced a fund raising drive to protect 82 acres of ecologically strategic upland forest and swamp wildlife habitat in Hadlyme on the headwaters of Whalebone Cove, one of the freshwater tidal wetlands that comprises the internationally celebrated Connecticut River estuary complex 
The new proposed preserve is part of a forested landscape just south of Hadlyme Four Corners and Ferry Road (Rt  148), and forms a large part of the watershed for Whalebone Creek, a key tributary feeding Whalebone Cove, most of which is a national wildlife refuge under the management of the US Fish & Wildlife Service 
The Land Trust said it hopes to name the new nature refuge in honor of William Hawthorne of Hadlyme, whose family has owned the property for several generations and who has agreed to sell the property to the Land Trust at a discount from its market value if the rest of the money necessary for the purchase can be raised by the Land Trust 
“This new wildlife preserve will represent a triple play for habitat conservation,” said Anthony Irving, chairman of the Land Trust’s Preservation Committee 
“First, it helps to protect the watershed feeding the fragile Whalebone Cove eco-system, which is listed as one of North America’s important freshwater tidal marshes in international treaties that cite the Connecticut River estuary as a wetland complex of global importance  Whalebone Creek, one of the primary streams feeding Whalebone Cove, originates from vernal pools and upland swamps just south of the Hawthorne tract on the Land Trust’s Ravine Trail Preserve and adjacent conservation easements and flows through the proposed preserve  Virtually all of the Hawthorne property comprises much of the watershed for Whalebone Creek 
“Second, the 82 acres we are hoping to acquire with this fund raising effort represents a large block of wetlands and forested wildlife habitat between Brush Hill and Joshuatown roads, which in itself is home to a kaleidoscope of animals from amphibians and reptiles that thrive in several vernal pools and swamp land, to turkey, coyote, bobcat and fisher  It also serves as seasonal nesting and migratory stops for several species of deep woods birds, which are losing habitat all over Connecticut due to forest fragmentation 
“Third, this particular preserve will also conserve a key link in the wildlife corridors that connects more than 1,000 acres of protected woodland and swamp habitat in the Hadlyme area ” Irving explained that the preserve is at the center of a landscape-scale wildlife habitat greenway that includes Selden Island State Park, property of the US Fish & Wild Life’s Silvio O Conte Wildlife Refuge, The Nature Conservancy’s Selden Preserve, and several other properties protected by the Lyme Land Conservation Trust 
“Because of its central location as a hub between these protected habitat refuges,” said Irving, “this preserve will protect forever the uninterrupted access that wildlife throughout the Hadlyme landscape now has for migration and breeding between otherwise isolated communities and families of many terrestrial species that are important to the continued robust bio-diversity of southeastern Connecticut and the Connecticut River estuary ”
Irving noted that the Hawthorne property is the largest parcel targeted for conservation in the Whalebone Cove watershed by the recently developed US Fish & Wildlife Service Silvio O Conte Wildlife Refuge Comprehensive Conservation Plan  Irving said the Land Trust hopes to create a network of hiking trails on the property with access from both Brush Hill Road on the east and Joshuatown Road on the west and connection to the Land Trust’s Ravine Trail to the south and the network of trails on the Nature Conservancy’s Selden Preserve 
Irving said there is strong support for the Land Trust’s proposal to preserve the property both within the Hadlyme and Lyme communities and among regional and state conservation groups  He noted letters of support have come from the Hadlyme Garden Club, the Hadlyme Public Hall Association, the Lyme Inland Wetlands & Watercourses Agency, the Lyme Planning and Zoning Commission, the Lyme Open Space Committee, the Lower Connecticut River Valley Council of Governments, the Lyme Garden Club, the Lyme Public Hall, The Nature Conservancy, The Silvio O Conte Refuge, the Connecticut River Watershed Council, and the Friends of Whalebone Cove, Inc 
He reported that between Hawthorne’s gift and several other pledges the Land Trust has already received commitments of 25 percent of the cost of the property



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Filed Under: Lyme, Outdoors, Top Story, vnn Old Lyme Tree Commission Celebrates Arbor Day April 29, 2016 by admin Leave a Comment Members of the three groups gather around the new oak tree  From left to right are Kathy Burton, Joanne DiCamillo, Joan Flynn  Anne Bing, Emily Griswold and Barbara Rayel 
Filed Under: Old Lyme, Outdoors, Top Story, Town Hall Enjoy a Tour of Private Gardens in Essex, June 4 April 28, 2016 by Adina Ripin Leave a Comment See this beautiful private garden in Essex on June 4 
ESSEX – On Saturday, June 4, from 10 a m  to 3 p m , plan to stroll through eight of the loveliest and most unusual private gardens in Essex  Some are in the heart of Essex Village while others are hidden along lanes most visitors never see  While exploring, you will find both formal and informal settings, lovely sweeping lawns and panoramic views of the Connecticut River or its coves  One garden you will visit is considered to be a ‘laboratory’ for cultivation of native plants  Master Gardeners will be available to point out specific features, offer gardening tips, and answer questions 
The garden tour is sponsored by the Friends of the Essex Library  Tickets are $25 in advance and $30 at the Essex Library the day of the event  Cash, checks, Visa or Master Card will be accepted  Tickets can be reserved by visiting the library or by completing the form included in flyers available at the library and throughout Essex beginning May 2  Completed forms can be mailed to the library  Confirmations will be sent to the email addresses on the completed forms 
Your ticket will be a booklet containing a brief description of each garden along with a map of the tour and designated parking  Tickets must be picked up at the library beginning at 9:45 a m  the day of the event 
Richard Conroy, library director, has said, “The Essex Library receives only about half of its operating revenue from the Town  The financial assistance we receive each year from the Friends is critical  It enables us to provide important resources such as Ancestry com and museum passes, as well as practical improvements like the automatic front doors that were recently installed  I urge you to help your Library by helping our Friends make this event a success! Thank you for your support ”
The tour will take place rain or shine  For more information, call 860-767-1560  All proceeds will benefit Friends of the Essex Library 
Filed Under: Outdoors Potapaug Presents Plum Island Program April 7, 2016 by admin Leave a Comment Potapaug Audubon presents “Preserving Plum Island” on Thursday, April 7, at 7 p m  at Old Lyme Town Hall, 52 Lyme St , Old Lyme, with guest speaker Chris Cryder, from the Preserve Plum Island Coalition 
Cryder will discuss the efforts to protect the island, which provides vital habitat for threatened and endangered birds 
This is a free program and all are welcome 
Filed Under: Old Lyme, Outdoors CT Legislators Support Study to Preserve Plum Island From Commercial Development March 28, 2016 by Jerome Wilson 1 Comment Aerial view of Plum Island lighthouse  (From Preserve Plum Island website)
Last Thursday, March 24, at a press conference in Old Saybrook, a triumvirate of Congressional legislators from Connecticut, State Senator Richard Blumenthal and US Representatives Joe Courtney (D-2nd District) and Rosa DeLauro (D-3rd District) confirmed their support for a study to determine the future of Plum Island located in Long Island Sound 
Members of the Plum Island Coalition — which has some 65 member organizations all dedicated to preserving the island — were in attendance to hear the good news 
The island still houses a high-security, federal animal disease research facility, but the decision has already been taken to move the facility to a new location in Kansas with an opening slated for 2022  The current facility takes up only a small percentage of the land on the island and significantly for environmentalists, the remainder of the island has for years been left to nature in the wild 
In supporting a federal study on the future of Plum Island, Sen  Blumenthal said, “This study is a step towards saving a precious, irreplaceable national treasure from developers and polluters  It will provide the science and fact-based evidence to make our case for stopping the current Congressional plan to sell Plum Island to the highest bidder ” He continued, “The stark truth is the sale of Plum Island is no longer necessary to build a new bioresearch facility because Congress has fully appropriated the funds  There is no need for this sale – and in fact, Congress needs to rescind the sale ” Congress, however, still has a law on the books that authorizes the sale of Plum Island land to the highest bidder  Therefore, opponents of the sale will have the burden of convincing Congress to change a law that is currently in place 
Filed Under: Old Lyme, Outdoors, Top Story, vnn Land Trusts’ Photo Contest Winners Announced March 24, 2016 by admin Leave a Comment Winner of the top prize, the John G  Mitchell Environmental Conservation Award – Hank Golet
The 10th Annual Land Trust’s Photo Contest winners were announced at a March 11 reception highlighting the winning photos and displaying all entered photos  Land trusts in Lyme, Old Lyme, Salem, Essex and East Haddam jointly sponsor the annual amateur photo contest to celebrate the scenic countryside and diverse wildlife and plants in these towns  The ages of the photographers ranged from children to senior citizens 
Hank Golet won the top prize, the John G  Mitchell Environmental Conservation Award, with his beautiful photograph of a juvenile yellow crowned night heron in the Black Hall River in Old Lyme  Alison Mitchell personally presented the award, created in memory of her late husband John G  Mitchell, an editor at National Geographic, who championed the cause of the environment 
William Burt, a naturalist and acclaimed wildlife photographer, who has been a contest judge for ten years, received a special mention  Judges Burt; Amy Kurtz Lansing, an accomplished art historian and curator at the Florence Griswold Museum; and Skip Broom, a respected, award-winning local photographer and antique house restoration housewright, chose the winning photographs from 219 entries 
The sponsoring land trusts – Lyme Land Conservation Trust, Essex Land Trust, the Old Lyme Land Trust, Salem Land Trust, and East Haddam Land Trust – thank the judges as well as generous supporters RiverQuest/ CT River Expeditions, Lorensen Auto Group, the Oakley Wing Group at Morgan Stanley, Evan Griswold at Coldwell Banker, Ballek’s Garden Center, Essex Savings Bank, Chelsea Groton Bank, and Alison Mitchell in honor of her late husband John G  Mitchell  Big Y and Fromage Fine Foods & Coffee provided support for the reception 
The winning photographers are:
John G  Mitchell Environmental Award, Hank Golet, Old Lyme
1st: Patrick Burns, East Haddam
2nd: Judah Waldo, Old Lyme
3rd: James Beckman, Ivoryton
Honorable Mention Gabriel Waldo, Old Lyme
Honorable Mention Sarah Gada, East Haddam
Honorable Mention Shawn Parent, East Haddam
Cultural/Historic
1st: Marcus Maronne, Mystic
2nd: Normand L  Charlette, Manchester
3rd: Tammy Marseli, Rocky Hill
Honorable Mention Jud Perkins, Salem
Honorable Mention Pat Duncan, Norwalk
Honorable Mention John Kolb, Essex
Landscapes/Waterscapes
1st: Cheryl Philopena, Salem
2nd: Marian Morrissette, New London
3rd: Harcourt Davis, Old Lyme
Honorable Mention Cynthia Kovak, Old Lyme
Honorable Mention Bopha Smith, Salem
1st: Mary Waldron, Old Lyme
2nd: Courtney Briggs, Old Saybrook
3rd: Linda Waters, Salem
Honorable Mention Pete Govert, East Haddam
Honorable Mention Marcus Maronne, Mystic
Honorable Mention Marian Morrissette, New London
First place winner of the Wildlife category – Chris Pimley
1st: Chris Pimley, Essex
2nd: Harcourt Davis, Old Lyme
Honorable Mention Thomas Nemeth, Salem
Honorable Mention Jeri Duefrene, Niantic
Honorable Mention Elizabeth Gentile, Old Lyme
The winning photos will be on display at the Lymes’ Senior Center for the month of March and Lyme Public Library in April  For more information go to lymelandtrust org 
Filed Under: Outdoors Old Lyme’s Open Space Commission Hosts Talk on Sea Level Rise, Salt Marsh Advance March 11, 2016 by admin 1 Comment The Town of Old Lyme’s Open Space Commission invites all interested parties to a workshop by Adam Whelchel, PhD, Director of Science at The Nature Conservancy’s Connecticut Chapter  The workshop will be held on Friday, March 11, at 9 a m  in the Old Lyme Town Hall 
Filed Under: Outdoors, Town Hall Inaugural Meeting of ‘Friends of Whalebone Cove’ Held, Group Plans to Protect Famous Tidal Wetland March 7, 2016 by admin Leave a Comment The newly formed ‘Friends of Whalebone Cove’ are working to preserve and protect the Cove’s fragile ecosystem 
A new community conservation group to protect Whalebone Cove, a freshwater tidal marsh along the Connecticut river in Hadlyme recognized internationally for its wildlife habitat, will hold its first organizational meeting this coming Sunday, March 6, at 4 p m 
Calling the group “Friends of Whalebone Cove” (FOWC), the organizers say their purpose is to “create a proactive, community-based constituency whose mission is to preserve and protect the habitat and fragile eco-systems of Whalebone Cove ”
Much of Whalebone Cove is a nature preserve that is part of the Silvio O  Conte National Wildlife Refuge (www fws gov/refuge/silvio_o_conte) under the jurisdiction of the U S  Fish & Wildlife Service (USFW)  The Refuge owns and manages 116 acres of marshland in Whalebone Cove and upland along its shores 
Prior to being taken over by USFW, the Whalebone Cove preserve was under the protection of The Nature Conservancy 
As part of the Connecticut River estuary, the Cove is listed in the Ramsar Convention on International Wetlands (www ramsar org) as tidal marshlands on the Connecticut River that constitute a “wetlands complex of international importance ”
The Ramsar citation specifically notes that Whalebone Cove has one of the largest stands of wild rice in the state  Except at high tide, most of the Cove is open marshland covered by wild rice stands with relatively narrow channels where Whalebone Creek winds its way through the Cove to the main stem of the Connecticut River 
Brian Slater, one of the group’s leaders who is filing the incorporation documents creating FOWC, said the creation of the organization was conceived by many of those living around the Cove and others in the Hadlyme area because of increased speeding motor boat and jet ski traffic in the Cove in recent years, damaging wetland plants and disrupting birds and other wildlife that make the Cove their home 
Slater said “Our goal is to develop a master plan for protection of the Cove through a collaborative effort involving all those who have a stake in Whalebone Cove – homeowners along its shores and those living nearby, the Silvio O  Conte Refuge, the Connecticut Department of Energy & Environmental Protection (DEEP), hunters, fishing enthusiasts, canoeing and kayaking groups, Audubon groups, the Towns of Lyme and East Haddam, The Nature Conservancy, the Connecticut River Watershed Council, the Lyme Land Conservation Trust, the Connecticut River Gateway Commission, and others who want to protect the Cove ”
“Such a plan”, said Slater, “should carefully evaluate the habitat, plants, wildlife and eco-systems of the Cove and the surrounding uplands and watershed and propose an environmental management plan that can be both implemented and enforced by those entrusted with stewarding the Cove and its fragile ecosystems for the public trust ”
FOWC has written a letter to Connecticut DEEP Commissioner Rob Klee asking that he appoint a blue ribbon commission to conduct the research and develop the management plan  FOWC also asked that Commissioner Klee either deny or defer approval on any applications for new docks in the Cove until the management plan can be developed and implemented  Currently there are no docks in the Cove 
“We are very concerned that the installation of docks permitted for motor boat use will greatly increase the amount of motorized watercraft in the Cove,” said Slater  “There’s already too much jet ski and speeding motorboat traffic in the Cove  Those living on the Cove have even seen boats towing water skiers crisscrossing the wild rice plants at high tide  Something has to be done to protect the birds and marine life that give birth and raise their young in the Cove ”
Slater urged all those “who treasure Whalebone Cove and the many species of birds, turtles, fish, reptiles, amphibians, beaver, and rare flora and fauna that make their home in it to attend the meeting, whether they live in the Hadlyme area or beyond ”
Expected to be at the meeting will be representatives from USFW, DEEP, the Connecticut River Watershed Council, and several other conservation organizations 
The meeting will be held at Hadlyme Public Hall, 1 Day Hill Rd , in Lyme, which is at the intersection of Ferry Rd  (Rte  148), Joshuatown Rd , and Day Hill Rd  Representatives from the Silvio O  Conte Refuge will make a short presentation on the history and mission of the Conte Refuge system, which includes nature preserves throughout the Connecticut River Valley in four states 
For more information, call 860-322-4021 or email fowchadlyme@gmail com
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ground_truth: Appointing a blue ribbon commission to conduct the research and develop the management plan and denying or defering approval on any applications for new docks in the Cove until the management plan can be developed and implemented.