bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Microtips with Self-Asligned Integrated Electrodes
Authors: Barros A. L. , Lopes A. T. , Carreno M. N.
Published: September 2007

In this work we present a method for the fabrication of silicon microtips with self-aligned anodes in order to obtain field emitting devices. The method is based on the anisotropic corrosion of the silicon substrate in KOH solutions and utilizes low stress SiOxNy films obtained by PECVD as masking material. These films are also utilized as structural material for mechanical support and electrical insulation of the electrodes. For the electrodes sputtered Cr films are utilized. Optical microscopy was utilized to determine the etch rate of the different stages during the microtip formation, in order to enable us to ascertain the total development time versus the initial mask dimensions. Matrixes with different number of microtips, 52 μm height and with diameter at the vertex bellow 1 μm, were fabricated and characterized. The results also show that the low stress SiOxNy film is essential to endure the corrosion process without structural damage.
Study of Nickel Silicide as Mask for Alkaline Solutions to V-grooves Fabrication
Authors: Mascaro A. R. , Goncalves L. C. , Mortimoto N. I.
Published: September 2007

In this work, we present a new fabrication process to obtain deep etching structures in a <100> silicon substrate using an alternative material (Ni2Si) deposited at low temperature (250{degree sign}C) as mask for alkaline solutions (KOH-27%-60{degree sign}C). V-grooves (60μ m deep) and square patternings were fabricated, showing that the Ni2Si is an appropriate alternative mask material, when compared with traditional ones as SiO2 or Si3N4. The stoichiometry of the film was investigated by RBS.
Zinc-Oxide Surface Acoustic Wave Device Fabrication
Authors: Santos Edval J. , Santos A. M.
Published: September 2007

Integration of a highly (002)-oriented zinc-oxide (ZnO) film onto an interdigitated (IDT) transducer has been demonstrated. The substrate materials used are alumina and glass plate. The IDT finger structure is made of nickel, and the ZnO layer has been deposited with the sol-gel method. The ZnO layer orientation has been optimized by applying experimental design and surface response techniques. The characteristic (002)-peak is observed by X-ray diffraction. The grain size is observed with scanning electron microscopy, and the oxide composition is measured with wavelength dispersive spectroscopy.
Photoresponse Analysis of Sensors Fabricated with Standard 2.0 μm CMOS Technology
Authors: Mestanza S. N. , Rodriguez E. , Doi I. , Diniz J. A. , Swart J. W. , Frateschi N. C.
Published: September 2007

This paper reports the fabrication and optical characterizations of CMOS sensors type junction, for two different geometries L and square, with areas 112x100 μm2 and 120x120 μm2, respectively. The sensor element is a photodiode implemented with n-well, using a CMOS process based on 2μm technology. An increase in the device photocurrent is observed when the reverse bias is increased. A wavelength shift for the maximum photocurrent peak was observed in the CMOS sensors after applying a bias voltage. Preliminary results indicate that sensors with more vertices exhibit a higher wavelength shift. This behavior could arise from both the changes in the depletion width and the effective device area. The output of the reverse-biased sensors is extremely linear with respect to the applied light intensity. Both responsivity and quantum efficiency exhibit a maximum peak at λ= 500 nm with values of 38 mA/W and 10.2 %, respectively.
A Theoretical Study of a Novel Multi-Terminal Pressure Sensor Based on the Transversal Piezoresistive Effect
Authors: Coraucci G. , Fruett F.
Published: September 2007

As an alternative to the pressure sensors based on the conventional silicon Wheatstone piezoresistive bridge or four-terminal piezotransducers, we propose a new topology based on a multiterminal piezotransducers. This topology improves both the sensor sensitivity and the Geometrical Correction Factor. The sensitivity of conventional piezotransducers is strongly limited by the wellknown short-circuit effects which are modeled by the geometrical correction factor. This multi-terminal topology maximizes the sensitivity and minimizes the correlation of the geometrical correction factor with the aspect ratio of the sensor layout.
Characterization of a P3HT- Si Heterojuntion for Solar Cells Applications
Authors: Nolasco J. C. , Estrada M. , Matsumoto Y. , Marsal L. F. , Pallares J.
Published: September 2007

The characteristics of Au/ P3HT (poly [3-hexylthiophene])/n-type crystalline silicon (n-c-Si)/Al heterojuntion diodes for solar cells applications are presented. A P3HT layer, 80 nm thick was spincoated on silicon substrate followed by thermal annealing and metal deposition. The capacitance-voltage measurements showed that the junction is abrupt. The mechanisms of conduction over temperature range from 300K to 360K is ohmic for voltages below 0.1 V and multi-step tunneling for medium voltage values from 0.1 V to 0.6V. Afterwards, the current-voltage characteristic is affected by a relatively high series resistance. The solar cell characteristics reported Voc=0.3 V and Isc=1.5 mA/cm2. The conversion efficiency of the structure was 0.65 %, which can ideally reach 3.25 % depending on the absorption in the top conductive layer.
Role of DDAH-1 in lipid peroxidation product-mediated inhibition of endothelial NO generation
Authors: Pope Arthur J. , Druhan Lawrence , Guzman Jorge E. , Forbes Scott P. , Murugesan Velayutham , Lu Deqin , Xia Yong , Chicoine Louis G. , Parinandi Narasimham L. , Cardounel Arturo J.
Published: September 2007

Altered nitric oxide (NO) biosynthesis is thought to play a role in the initiation and progression of atherosclerosis and may contribute to increased risk seen in other cardiovascular diseases. It is hypothesized that altered NO bioavailability may result from an increase in endogenous NO synthase (NOS) inhibitors, asymmetric dimethly araginine (ADMA), and NG-monomethyl arginine, which are normally metabolized by dimethyarginine dimethylamine hydrolase (DDAH). Lipid hydroperoxides and their degradation products are generated during inflammation and oxidative stress and have been implicated in the pathogenesis of cardiovascular disorders. Here, we show that the lipid hydroperoxide degradation product 4-hydroxy-2-nonenal (4-HNE) causes a dose-dependent decrease in NO generation from bovine aortic endothelial cells, accompanied by a decrease in DDAH enzyme activity. The inhibitory effects of 4-HNE (50 μM) on endothelial NO production were partially reversed with l-Arg supplementation (1 mM). Overexpression of human DDAH-1 along with antioxidant supplementation completely restored endothelial NO production following exposure to 4-HNE (50 μM). These results demonstrate a critical role for the endogenous methylarginines in the pathogenesis of endothelial dysfunction. Because lipid hydroperoxides and their degradation products are known to be involved in atherosclerosis, modulation of DDAH and methylarginines may serve as a novel therapeutic target in the treatment of cardiovascular disorders associated with oxidative stress.
Noninvasive assessment of the effects of glucagon on the gastric slow wave
Authors: Bradshaw L. Alan , Sims Jared A. , Richards William O.
Published: September 2007

Hyperglycemic effects on the gastric slow wave are not well understood, and no studies have examined the effects that hyperglycemia has on gastric slow wave magnetic fields. We recorded multichannel magnetogastrograms (MGGs) before and after intravenous administration of glucagon and subsequent modest hyperglycemia in 20 normal volunteers. Normal slow waves were evident in baseline MGG recordings from all 20 subjects, but within 15 min after glucagon had been given, we noted significant effects on MGG signals. In addition to an overall decrease in the slow wave frequency from 2.9 ± 0.5 cycles per min (cpm) to 2.2 ± 0.1 cpm ( P < 0.05), we observed significant changes in the number and range of spectral peaks recorded. Furthermore, the propagation velocity determined from surface current density maps computed from the multichannel MGG decreased significantly (7.1 ± 0.8 mm/s to 5.0 ± 0.3 mm/s, P < 0.05). This is the first study of biomagnetic effects of hyperglycemia in normal subjects. Our results suggest that the analysis of the MGG provides parameter quantification for gastric electrical activity specific to and characteristic of slow wave abnormalities associated with increased serum glucose by injection of glucagon.
Determination of gastric emptying in nonobese diabetic mice
Authors: Choi Kyoung Moo , Zhu Jin , Stoltz Gary J. , Vernino Steven , Camilleri Michael , Szurszewski Joseph H. , Gibbons Simon J. , Farrugia Gianrico
Published: September 2007

Animal studies on diabetic gastroparesis are limited by inability to follow gastric emptying changes in the same mouse. The study aim was to validate a nonlethal gastric emptying method in nonobese diabetic (NOD) LtJ mice, a model of type 1 diabetes, and study sequential changes with age and early diabetic status. The reliability and responsiveness of a [13C]octanoic acid breath test in NOD LtJ mice was tested, and the test was used to measure solid gastric emptying in NOD LtJ mice and nonobese diabetes resistant (NOR) LtJ mice. The13C breath test produced results similar to postmortem recovery of a meal. Bethanechol accelerated gastric emptying [control: 92 ± 9 min; bethanechol: 53 ± 3 min, mean half emptying time ( T1/2) ± SE], and atropine slowed gastric emptying (control: 92 ± 9 min; atropine: 184 ± 31 min, mean T1/2± SE). Normal gastric emptying ( T1/2) in nondiabetic NOD LtJ mice (8–12 wk) was 91 ± 2 min. Aging had differing effects on gastric emptying in NOD LtJ and NOR LtJ mice. Onset of diabetes was accompanied by accelerated gastric emptying during weeks 1–2 of diabetes. Gastric emptying returned to normal by weeks 3–5 with no delay. The [13C]octanoic acid breath test accurately measures gastric emptying in NOD LtJ mice, is useful to study the time course of changes in gastric emptying in diabetic NOD LtJ mice, and is able to detect acceleration in gastric emptying early in diabetes. Opposing changes in gastric emptying between NOD LtJ and NOR LtJ mice suggest that NOR LtJ mice are not good controls for the study of gastric emptying in NOD LtJ mice.
Voluntary run training but not estradiol deficiency alters the tibial bone-soleus muscle functional relationship in mice
Authors: Warren Gordon L. , Moran Amy L. , Hogan Harry A. , Lin Angela S. , Guldberg Robert E. , Lowe Dawn A.
Published: September 2007

The study's objective was to investigate how estrogen deficiency and run training affect the tibial bone-soleus muscle functional relationship in mice. Female mice were assigned into one of two surgical conditions, ovariectomy (OVX) or sham ovariectomy (sham), and one of two activity conditions, voluntary wheel running (Run) or sedentary (Sed). To determine whether differences observed between OVX and sham conditions could be attributed to estradiol (E2), additional OVX mice were supplemented with E2. Tibial bones were analyzed for their functional capacities, ultimate load, and stiffness. Soleus muscles were analyzed for their functional capacities, maximal isometric tetanic force (Po), and peak eccentric force. The ratios of bone functional capacities to those of muscle were calculated. The bone functional capacities were affected by both surgical condition and activity but more strongly by surgical condition. Ultimate load and stiffness for the sham group were 7–12% greater than those for OVX animals ( P = 0.002), whereas only stiffness was greater for Run than for Sed animals (9%; P = 0.015). The muscle functional capacities were affected by both surgical condition and activity; however, in contrast to the bone, the muscle was more affected by activity. Po and peak eccentric force were 10–21% greater for Run than for Sed animals ( P ≤ 0.016), whereas only Po was greater in sham than in OVX animals (9%; P = 0.011). The bone-to-muscle ratios of functional capacities were affected by activity but not by surgical condition or E2 supplementation. Thus a mismatch of bone-muscle function occurred in mice that voluntarily ran on wheels, irrespective of estrogen status.
Therapeutic potential of synchronized gastric electrical stimulation for gastroparesis: enhanced gastric motility in dogs
Authors: Zhu Hongbing , Sallam Hanaa , Chen Dennis D. , Chen Jiande D. Z.
Published: September 2007

The aim of this study was to determine the effects and mechanism of synchronized gastric electrical stimulation (SGES) on gastric contractions and gastric emptying. The first experiment was designed to study the effects of SGES on antral contractions in four randomized sessions. Sessions 1 (control) and 2 (atropine) were performed in the fasting state, composed of three 30-min periods (baseline, stimulation, and recovery). Sessions 3 (control) and 4 (SGES performed during 2nd 20-min period) were performed in the fed state, consisting of two 20-min periods; glucagon was injected after the first 20-min recording. The second experiment was designed to study the effect of SGES on gastric emptying and consisted of two sessions (control and SGES). SGES was delivered with train duration of 0.5–0.8s, pulse frequency of 40 Hz, width of 2 ms, and amplitude of 4 mA. We found that 1) SGES induced gastric antral contractions in the fasting state. The motility index was 1.3 ± 0.5 at baseline and 6.1 ± 0.7 ( P = 0.001) during SGES. This excitatory effect was completely blocked by atropine. 2) SGES enhanced postprandial antral contractions impaired by glucagon. 3) SGES significantly accelerated glucagon-induced delayed gastric emptying. Gastric emptying was 25.5 ± 11.3% without SGES and 38.3 ± 10.7% with SGES ( P = 0.006 vs. control). This novel method of SGES induces gastric antral contractions in the fasting state, enhances glucagon-induced antral hypomotility in the fed state, and accelerates glucagon-induced delayed gastric emptying. The effect of SGES on antral contractions is mediated via the cholinergic pathway.
ANG II induces c-Jun NH2-terminal kinase activation and proliferation of human mesangial cells via redox-sensitive transactivation of the EGFR
Authors: Ding Guixia , Zhang Aihua , Huang Songming , Pan Xiaoqin , Zhen Guo , Chen Ronghua , Yang Tianxin
Published: September 2007

We previously showed that ANG II induces mesangial cell (MC) proliferation via the JNK-activator protein-1 pathway. The present study attempted to determine the upstream mediators of JNK activation, with emphasis on reactive oxygen species (ROS) and the epidermal growth factor (EGF) receptor (EGFR). In cultured human MCs (HMCs), as early as 3 min, ANG II time dependently increased intracellular ROS production, which was sensitive to 10 μM diphenyleneiodonium sulfate and 500 μM apocynin, two structurally distinct NADPH oxidase inhibitors. In contrast, inhibitors of other oxidant-producing enzymes, including the mitochondrial complex I inhibitor rotenone, the xanthine oxidase inhibitor allopurinol, the cyclooxygenase inhibitor indomethacin, the lipoxygenase inhibitor nordihydroguiaretic acid, the cytochrome P-450 oxygenase inhibitor ketoconazole, and the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester, were without effect. ANG II-induced ROS generation was inhibited by the angiotensin type 1 receptor antagonist losartan (10 μM) but not the angiotensin type 2 receptor antagonist PD-123319 (10 μM). ANG II induced translocation of p47phoxand p67phoxfrom the cytosol to the membrane. The antioxidants almost abolished the ANG II mitogenic response, as assessed by [3H]thymidine incorporation and cell number, associated with a remarkable blockade of the activation of EGFR (90% inhibition) and JNK (83% inhibition). The EGFR inhibitor AG-1478 was able to mimic the effect of antioxidants, in that it inhibited the mitogenic response and the JNK activation following ANG II treatment. Together, these data suggest that the ROS-EGFR-JNK pathway is involved in transducing the proliferative effect of ANG II in cultured HMCs.
Overexpression of upstream stimulatory factor 2 accelerates diabetic kidney injury
Authors: Liu Shu , Shi Lihua , Wang Shuxia
Published: September 2007

Diabetic nephropathy is the most common cause of end-stage renal failure in the United States. Hyperglycemia is an important factor in the pathogenesis of diabetic nephropathy. Hyperglycemia upregulates the expression of transforming growth factor-β (TGF-β), which stimulates extracellular matrix deposition in the kidney, contributing to the development of diabetic nephropathy. Our previous studies demonstrated that the transcription factor, upstream stimulatory factor 2 (USF2), was upregulated by high glucose, which bound to an 18-bp sequence in the thrombospondin 1 (TSP1) gene promoter and regulated high glucose-induced TSP1 expression and TGF-β activity in mesangial cells, suggesting that USF2 might play a role in the development of diabetic nephropathy. In the present studies, we examined the effect of overexpression of USF2 on the development of diabetic nephropathy. Type 1 diabetes was induced in USF2 transgenic mice [USF2 (Tg)] and their wild-type littermates (WT) by injection of streptozotocin. Four groups of mice were studied: control WT, control USF2 (Tg), diabetic WT, and diabetic USF2 (Tg). Mice were killed after 15 wk of diabetes onset. At the end of studies, control USF2 (Tg) mice (∼6 mo old) exhibited increased urinary albumin excretion. These mice also exhibited glomerular hypertrophy, accompanied by increased TSP1, active TGF-β, fibronectin accumulation in the glomeruli compared with control WT littermates. Type 1 diabetes onset further augmented the urinary albumin excretion and glomerular hypertrophy in the USF2 (Tg) mice. These findings suggest that overexpression of USF2 accelerates the development of diabetic nephropathy.
Influence of hyperoxia on skin vasomotor control in normothermic and heat-stressed humans
Authors: Yamazaki Fumio , Takahara Kazuo , Sone Ryoko , Johnson John M.
Published: September 2007

Hyperoxia induces skin vasoconstriction in humans, but the mechanism is still unclear. In the present study we examined whether the vasoconstrictor response to hyperoxia is through activated adrenergic function ( protocol 1) or through inhibitory effects on nitric oxide synthase (NOS) and/or cyclooxygenase (COX) ( protocol 2). We also tested whether any such vasoconstrictor effect is altered by body heating. In protocol 1 ( n = 11 male subjects), release of norepinephrine from adrenergic terminals in the forearm skin was blocked locally by iontophoresis of bretylium (BT). In protocol 2, the NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME) and the nonselective COX antagonist ketorolac (Keto) were separately administered by intradermal microdialysis in 11 male subjects. In the two protocols, subjects breathed 21% (room air) or 100% O2in both normothermia and hyperthermia. Skin blood flow (SkBF) was monitored by laser-Doppler flowmetry. Cutaneous vascular conductance (CVC) was calculated as the ratio of SkBF to blood pressure measured by Finapres. In protocol 1, breathing 100% O2decreased ( P < 0.05) CVC at the BT-treated and at untreated sites from the levels of CVC during 21% O2breathing both in normothermia and hyperthermia. In protocol 2, the administration of l-NAME inhibited ( P < 0.05) the reduction of CVC during 100% O2breathing in both thermal conditions. The administration of Keto inhibited ( P < 0.05) the reduction of CVC during 100% O2breathing in hyperthermia but not in normothermia. These results suggest that skin vasoconstriction with hyperoxia is partly due to the decreased activity of functional NOS in normothermia and hyperthermia. We found no significant role for adrenergic mechanisms in hyperoxic vasoconstriction. Decreased production of vasodilator prostaglandins may play a role in hyperoxia-induced cutaneous vasoconstriction in heat-stressed humans.
Comparison of Bandwidths in the Inferior Colliculus and the Auditory Nerve. I. Measurement Using a Spectrally Manipulated Stimulus
Authors: Mc Laughlin Myles , Van de Sande Bram , van der Heijden Marcel , Joris Philip X.
Published: September 2007

A defining feature of auditory systems across animal divisions is the ability to sort different frequency components of a sound into separate neural frequency channels. Narrowband filtering in the auditory periphery is of obvious advantage for the representation of sound spectrum and manifests itself pervasively in human psychophysical studies as the critical band. Peripheral filtering also alters coding of the temporal waveform, so that temporal responses in the auditory periphery reflect both the stimulus waveform and peripheral filtering. Temporal coding is essential for the measurement of the time delay between waveforms at the two ears—a critical component of sound localization. A number of human psychophysical studies have shown a wider effective critical bandwidth with binaural stimuli than with monaural stimuli, although other studies found no difference. Here we directly compare binaural and monaural bandwidths (BWs) in the anesthetized cat. We measure monaural BW in the auditory nerve (AN) and binaural BW in the inferior colliculus (IC) using spectrally manipulated broadband noise and response metrics that reflect spike timing. The stimulus was a pair of noise tokens that were interaurally in phase for all frequencies below a certain flip frequency (fflip) and that had an interaural phase difference of π above fflip. The response was measured as a function of fflip and, using a separate stimulus protocol, as a function of interaural correlation. We find that both AN and IC filter BW depend on characteristic frequency, but that there is no difference in mean BW between the AN and IC.
Plasticity in Sublesionally Located Neurons Following Spinal Cord Injury
Authors: Lapointe Nicolas P. , Ung Roth-Visal , Guertin Pierre A.
Published: September 2007

Neuronal plasticity has been traditionally associated with learning and memory processes in the hippocampal regions of the brain. It is now generally accepted that plasticity phenomena are also associated with other kinds of cellular changes and modifications occurring in all areas of the CNS after injury or intense neuronal activity. For instance, spinal cord injuries have been associated with a series of cellular modifications and adaptations taking place distally in sublesional areas. Some of these modifications include changes in the expression of immediate early genes (e.g., c-fos and nor-1), TNF-alpha, preprodynorphin, neurotrophic factors (e.g., BDNF and NT-3), and several subtypes of transmembranal receptors (e.g., 5-HT1Aand 5-HT2A). This review constitutes an update of the current knowledge regarding this broadly defined plasticity phenomenon that occurs spontaneously or can be modulated by training in sublesional segments of the spinal cord. Spinal cord plasticity is an increasingly popular field of research, believed by many as being a complex phenomenon that may contribute to the development of innovative therapeutics and rehabilitative approaches for spinal cord injured patients.
Ultraviolet Laser Photoablation of Polymers: A Review and Recent Results
Authors: Lazare Sylvain , Granier Vincent
Published: September 2007

The evolution since 1982, of far‐UV laser photoablation of polymers is described. The experimental data
can be fitted by using a dynamic model which states that the irradiated interface moves at a rate
proportional to the difference between, the intensity reaching it, and the ablation threshold intensity

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.
The screening effect of the ablated gaseous products is taken into account. The experimental etch depth
versus fluence, obtained with our new quartz crystal microbalance technique, can be fitted by adjusting
two parameters of this model; the mean absorption coefficient of the products

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and the so‐called ablation
rate constant k, which is the etch rate for

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MW/cm2. These two parameters are wavelength
dependent. The model allows also the calculation of the dose of absorbed energy as a function of depth in
the material. For each layer of the ablated depth, the dose absorbed before and after (reabsorption of the
gas products) ablation are distinguished. The dose of reexcitation varies highly with fluence and the
distribution of gas products broadens accordingly. However, primary products need to be studied. Surface
products are formbd on the final surface, during the postablation phase of the pulsed irradiation. The
probable mechanism of the evolution of excitation energy is discussed, with stress on the elementary steps
leading to heat production.

The perspectives of evolution of etching and patterning polymer surfaces by far‐UV photoablation are
high in basic research and technology.
Nonlinear Laser Chemistry of Maleic Acid
Authors: Leupold D. , Ehlert J. , Oberländer S. , Klose E. , Mory S. , Winkelmann G.
Published: September 2007

With reference to recent laser investigations of excited state reactions of maleic acid in Letokhov’s group,
relevant excited state constants were determined by means of a physico‐mathematical methods package of
nonlinear absorption and the excited state populations were calculated for the experimental conditions.
Based on this, a change of the assignment of the found reactions to excited states is suggested in the
following manner: dimerization in T1 and maleic acid formation in a higher excited triplet.
Laser Induced Fluorescence of Resulting From the Thermal Energy Dissociative Charge Transfer Reaction
Authors: Lemaire j. , Marx R. , Savary F. Morlet
Published: September 2007

The vibrational (and rotational) energy distribution of ions
produced in the He+/N2O charge transfer reaction at thermal
energy has been measured by laser induced fluorescence using
an Ion Cyclotron Resonance cell to store the ions. Vibrational
levels up to V" = 5 have been observed.

The relaxation processes experienced by the (X) ions before
laser detection are discussed.
Spectroscopy and Dynamics of Benzonitrile‐Enzene Complexes in A Supersonic Free‐Jet
Authors: Lahmani F. , Lardeux-Dedonder C. , Zehnacker A.
Published: September 2007

Excitation and fluorescence spectra of benzonitrile‐benzene and toluene complexes seeded in helium and
expanded in a supersonic free jet reveals two types of transition attributed to the coexistence of two
isomeric forms. One consists of narrow bands in both excitation and emission and is characteristic of
wealdy perturbed van tier Waals complexes. The other involves broadened absorption and gives rise to an
exciplex type emission.
Picosecond Absorption Spectroscopy of Energy Transfer Processes in Polymethine Dyes
Authors: Feller K. -H. , Gadonas R. , Krasauskas V.
Published: September 2007

Results are presented of time‐resolved absorption investigations of energy transfer processes between a
polymethine dye and an iron complex dye (dye E). For the first time the acceptor molecule transient
absorption depletion generated by energy transfer from an excited donor was observed. The decay time of
the acceptor deactivation (≈ 140 Ps) in the presence of the energy donor agrees very well with the S1‐state
lifetime of the energy donor.
Reaction Dynamics of Electronically Excited Barium Atoms With Free Molecules and Molecular Clusters
Authors: Mestdagh J. M. , Alcaraz C. , Berlande J. , Cuvellier J. , Gustavsson T. , Meynadier P. , De Pujo P. , Sublemontier O. , Visticot J. P.
Published: September 2007

In this review article we describe some recent results obtained in our laboratory. The successful
combination of crossed molecular beam techniques and various laser excitation schemes has been used to
study chemiluminescent reactions of ground and excited electronic states of barium with free molecules
and molecular clusters. Studies include the identification of reaction products in cases where many
chemiluminescent reaction channels are opened. The case of Ba

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reacting with
H20, methanol, ethanol, propanol‐1, propanol‐2, methyl‐2, propanol‐2, butanol‐l, allyl alcohol, dimethyl
ether, diethyl ether and diallyl ether is examined. A reaction mechanism is proposed which accounts
for all these reactions. Studies reported in this review also include the unravelling of reaction dynamics
where various forms of energy are mixed (electronic and kinetic energy). This is shown in studies of
Ba

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reactions. Finally the role of molecular clusters as reactant is examined. Evidence
is provided that clusters of N20, H20 and CO2, in collision with Ba

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, do not lead efficiently to
both reactive and non reactive luminescent exit channels.
Uv Multiphoton Induced Chemistry of Nitrobenzene in Solution
Authors: Belbruno Joseph J. , Siuzdak Gary , North Simon
Published: September 2007

The technique of Multiphoton Induced Chemistry (MPIC) has been employed to initiate ion‐molecule
chemistry of organic molecules in solution. We report one of the first examples of the use of liquid phase
multiphoton ionization (MPI) to prepare organic cations, which then react with the solvent in ionmolecule
processes. The products obtained in this chemical sequence are significantly different from those
observed in conventional or multiphoton‐induced neutral chemistry in the same solvent. The particular
example explored in this work is the reactivity of the nitrobenzene cation in methanol solvent. Products of
the ion‐molecule chemistry, detected by gas chromatography/mass spectrometry, are phenol and benzyl
alcohol. These products depend upon the square of the laser intensity. It is shown by ionization current
measurements in a conductance cell, that ionic species are produced as precursors to the observed
products. The implications of this application of MPI are briefly discussed. A preliminary report on the
unimolecular chemistry of the highly excited neutral molecule is also included. The product of this channel
is nitrosobenzene. It is shown, in this case, that the reactive state is most likely a highly vibrationally
excited ground state molecule, not the lowest triplet level invoked in conventional photochemistry.
Recent Studies on Coupling Between Translational Transport andReactivity at Molecular Scale: Models and Experimentation
Authors: Andre J. C. , Baros F. , Bouchy A. , Bouchy M. , Dong W. , Duhamel J. , Reis A. T. , Sousa E. , Viriot M. L.
Published: September 2007

Different theoretical models are presented concerning diffusion‐influenced reactions. Pulsed laser
systems allow time resolved fluorescence measurements of these kinetic phenomena. The connection
between theory and experimentation is illustrated.
Benzylchlorocarbene: UV Absorption Spectrum, Kinetics for 1,2‐H Migration and Mechanism for Reaction WithAcetic Acid as Determined by Combined Continuous and Laser‐Flash Photolysis
Authors: Bonneau R. , Liu M. T. H. , Subramanian R. , Linkletter B. , Stevens I. D. R.
Published: September 2007

The UV absorption spectrum of benzylchlorocarbene, generated by laser flash photolysis of 3‐chloro‐3‐
benzyldiazirine, has been observed in the 290‐330 nm range. The lifetime of this species, 18 ns at 25°C, is
determined by the rate of the 1,2‐H migration to produce chlorostyrenes. Quenching rate constants of this
carbene by acetic acid and tetramethylethylene have been measured. Comparison of this kinetic data with
the quantitative analysis of the products obtained under continuous irradiation gives further insight into
the mechanisms of carbene‐acetic acid reactions.
Doppler Measurement of Differential Cross Sections in Crossed BeamExperiments: Dependence of the Detection Sensitivity With the Product Velocity
Authors: Billy N. , Girard B. , Gouédard G. , Vigué J.
Published: September 2007

Differential cross sections can be measured as a function of the internal state of a reaction product thanks
to the analysis of the Doppler profile of the laser induced fluorescence detection line. This analysis is
complicated by two effects: first, the LIF signal intensity depends on the interaction time of the molecule
with the laser, and this time depends on the scattering angle, second, the angular and velocity distributions
of the beams have non negligible widths. We present here a treatment of these effects in the case of the

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reaction for which we have measured the differential cross section by this technique. The same
formalism is also applied to the deduction of the rovibrational distribution of the products from the
relative intensities of the LIF lines.
UV Photoablation of Atherosclerotic Lesions. Application in Cardiology
Authors: Avrillier S. , Ollivier J. P. , Gandjbakhch I. , Delettre E. , Bussieref J. L. , Tinet E.
Published: September 2007

Various methods for the ablation of the atherosclerotic material that fills the coronary arteries are under
investigation. Among them laser coronary angioplasty is one of the most promising. In this paper we show
that the XeCl excimer laser (308 nm) offers many advantages which make it appear as a rather good tool.
In vitro studies demonstrate the ability of precise control of the UV photoablation process, there is no
thermal damage and the risk of perforation is reduced. A suitable laser‐fiber optic delivery system has
been developed and the results of the first in vivo procedures are very encouraging.
Periodic Orbits as a Probe to Reveal Exotic States inVibrationally Excited Molecules: The Saddle‐Node States
Authors: Farantos Stavros C.
Published: September 2007

We present theoretical results which show the existence of isomerizing localized quantum states above
potential barriers for the excited 1B2 states of SO2 and O3. These states are assigned by periodic orbits
which emerge from saddle‐node bifurcations, the characteristic of which is the simultaneous generation
of two families of periodic orbits one stable and one unstable. Similar isomerizing states and bifurcations
have been found for other molecules, and this leads to the conclusion, that the appearance of saddle‐node
type states may be a generic phenomenon for molecular potentials with barriers.
Two‐Photon Resonant Third Harmonic Generation IN Hg
Authors: Koudoumas E. , Efthimiopoulos T.
Published: September 2007

Third‐harmonic generation in Hg vapors, using the two‐photon resonance 61S0–81S0 transition is theoretically
and experimentally investigated. Calculations of the Hg contribution to the phase mismatch are
presented and the effects of the absorption of the radiation, the population transfer, the saturation, and
the ionization on the efficiency of the system are considered. It is shown that the population transfer is
the dominant mechanism affecting the efficiency.
2+1 (2+2) Rempi‐Tof Study of the Lowest Rydberg States (6s, 6s’)of Methyl and Propyl Iodides
Authors: Couris S. , Agapaki P. , Brint Paul
Published: September 2007

Resonance enhanced multiphoton ionisation (REMPI) combined with time of flight mass analysis under
supersonic beam conditions has been used to investigate the nature of the UV absorption spectra broadening
of the 6s Rydberg states in alkyl iodides.
The increase of the size of the alkyl substituent was associated with this broadening although it was
not known whether this was due to an increase in vibronic activity or to Rydberg state substituent
interaction.
The Jet cooled REMPI spectra of methyl and propyl iodide obtained have confirmed that the source
of broadening of the 6s Rydberg states is solely due to vibronic activity of the alkyl group attached to
the spectroscopic chromophore.
Laser Pyrolysis of CH3Br
Authors: Chang Hua , Hsieh Jang Ching
Published: September 2007

Laser pyrolysis of CH3Br by a strong laser irradiation was studied in this work. Besides a fine needle of
solid carbon was deposited at the surface on the substrate, HBr and CH4, were found as gaseous products
with a ratio of 2:1. Small amount of C2H2 was also detected. The variation in the pressures of CH3Br,
HBr and CH4 were measured by Raman spectroscopy. It indicated that the decomposition of CH3Br was
first order with respect to CH3Br. The reaction mechanism of the laser pyrolysis was suggested as follows:
After gaining enough energy at the hot spot, CHaBr was pyrolyzed to produce HBr and CH2 which then
reacted with CH3Br to form CH4, and solid carbon.
On the Development of New VUV and UV Solid State Laser Sources for Photochemical Applications
Authors: Cefalas A. C. , Dubinskii M. A. , Sarantopoulou E. , Abdulsabirov R. Yu. , Korableva S. L. , Naumov A. K. , Semashko V. V. , Nicolaides C. A.
Published: September 2007

Laser action in the VUV and UV region of the spectrum at 172 nm and at 260 nm had been obtained
from LaF3:Nd3+and LiYF4:Nd3+ crystals respectively when they were pumped with an F2 pulsed discharge
molecular laser at 157 nm.
The fluorescence spectrum of LiYF4:HO3+ monocrystals using the same pumping source has been
obtained as well and it suggests that this crystal can be used for generating tunable coherent VUV and
UV radiation. This finding opens new prospects for the development of a new class of solid state VUV
and UV laser sources for photochemical applications.
Absorption and Emission Spectra for C60 Anions
Authors: Kato Tatsuhisa
Published: September 2007

Absorption spectra are detected for and produced electrolytically in solution at room temperature.
Theoretical analysis of the spectrum of by CNDO/S calculations gives an interpretation of the characteristic
near‐IR bands, the weak visible bands, and the strong bands in the UV region. The emission
spectrum of is a mirror image of the near‐IR absorption band, and the detection of the emission
reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of is
characterized by a similar orbital picture to that of . Further laser experiments of significance are
proposed.
Laser‐Induced Negative Ionization: The SF6 + Ba Surface Reaction
Authors: Aspas J. Castaño , Ureña A. González
Published: September 2007

This paper reports on the results about the SF6 + Ba (surface) reactions as a function of the vibrational
excitation of the polyatomic molecule. A thermal, vibrationally excited by a tunable CO2 laser, SF6 beam
is collided with a Ba surface target under high vacuum conditions. The total negative ion yield is measured
as a function of the laser wavelength. Preliminary results show a strong vibrational enhancement of the
beam‐surface reactions indicating important laser‐assisted negative ionization effects. The results are
discussed in the light of several possible reaction mechanisms.
New Scheme for Extracting Molecular Dynamics from Spectra: Case Study on Vibrationally Highly Excited Acetylene
Authors: Yamanouchi Kaoru , Miyawaki Jun , Tsuchiya Soji , Jonas David M. , Field Robert W.
Published: September 2007

Three types of analyses: generalized conventional spectroscopic analysis, statistical analysis, and hierarchical
analysis, by which we aim to extract dynamical information from the complex spectrum of small
polyatomic molecules are reviewed by referring to recent studies on vibrationally highly excited acetylene.
A convolution analysis, one type of hierarchical analysis, is performed on the dispersed fluorescence
spectrum of acetylene to demonstrate its practical applicability. Based on previous studies, as well as
on the convolution analysis, a systematic and efficient procedure to treat such complex spectra is
discussed.
A Question of Laser Intensity
Authors: McRae G. A.
Published: September 2007

Parameterization of laser intensity requires different practical definitions which depend on
the temporal and spatial characteristics of the optical beam. Comparison of observations
obtained using different lasers, with similar numerical values of intensity, will prove misleading
for non‐linear phenomena. The invariant quantities that each experiment should
have in common are the determinable model parameters.
Comment: Reply to Comment on “Dynamics of the B and a  3Π(1u) States of Chlorine by Laser Induced Fluorescence”
Authors: Martínez E. , Basterrechea F. J. , Cabañas B. , Puyuelo P. , López M. R.
Published: September 2007

The comment of Billy et al.1 on our paper about the dynamics of the B and A states of chlorine2
emphasizes mainly two points: a) our results about the radiative decay rate of the B state of Cl2 are
incorrect, because our experimental system is unable to measure the true long lifetimes of this state; b)
both A  3Π(1u) and  1Π(1u) states contribute to the Coriolis predissociation in the B state, in contradiction
with our mechanism, which excludes the  1Π(1u) state.
Laser Spectroscopic Investigation of High Rydberg States of no:Decay Dynamics Near the First Ionization Threshold
Authors: Fujii Asuka , Morita Norio
Published: September 2007

With a state‐selective laser excitation, two main decay processes, autoionization and predissociation, in
vibrational superexcited Rydberg states (n = 8–12, l = s, p, and f, v = 1) of NO have been studied,
directly detecting not only NO+ ions generated by autoionization but also every fragment atom produced
by predissociation. In addition, the v = 0 states lying below the ionization threshold have also been
investigated with the same method, and the comparison between the two results has more clearly
elucidated the competing behavior of the decay processes in the above‐threshold states (v = 1). As a
result, for the v = 1 state, it has been shown that predissociation is the main decay process in the np
Rydberg states, while autoionization is dominant in the ns Rydberg states. For the nf Rydberg states,
the N(4S) + O(3P) predissociation channel, which has not been emphasized in previous studies, has been
found to play an important role in the decay dynamics both above and below the ionization threshold.
Photodissociation Spectroscopy of
Authors: Ohashi Kazuhiko , Nakai Yasuhiro , Shibata Takeshi , Nishi Nobuyuki
Published: September 2007

The photodissociation spectrum of is obtained from the yields of fragment ion as a function
of photodissociation wavelength in the 400–1400 nm region. Two bands at 440 and 580 nm are attributed
to the C ← X and the B ← X local excitation (LE) bands, respectively. Both the most intense band at
920 nm and relatively weak one at 1160 nm are assigned to charge resonance (CR) bands. The red‐shift
of the B ← X band from that of and the cross sections at the CR bands much larger than those
at the LE bands are consistent with a sandwich structure for . The appearance of the two CR
bands is explained on the basis of displaced sandwich structures for .
Identification of Excited Gerade States of Molecular Hydrogen with Extreme Ultraviolet‐Visible Double Resonance Excitation Technique
Authors: Ishii Juntarou , Tsukiyama Koichi , Uehara Kiyoji
Published: September 2007

Extreme ultraviolet‐visible double resonance excitation has been employed to populate selected rovibronic
levels of the EF , H , I 1Πg and J 1Δg states of H2 lying in the range between 115,000 and
117,600 cm-1 above the ground state X . Tunable coherent extreme ultraviolet radiation, generated
by a four‐wave mixing process in Xe, prepares H2 in the intermediate B (v = 6, J) state. Subsequent absorption of the visible laser radiation brings H2 to the higher gerade states and the fluorescence light
from these states is detected. Term values of 41 rovibronic levels in these gerade states, including 23
previously unidentified levels, were determined. The single rovibronic fluorescence lifetimes were also
measured under the collision‐free condition. The fluorescence lifetimes of the EF states exhibited
significant rotational dependences. The nonadiabatic coupling among the adiabatic upper gerade vibronic
states explained the observed rotational dependences successfully.
Rotational Coherence Spectroscopy and Excited‐State Dynamics of Tolane and its Van Der Waals Complexes with Argon and Nitrogen
Authors: Ohline Shane M. , Romascan Joann , Felker Peter M.
Published: September 2007

We report the results of rotational coherence spectroscopy on tolane, tolane–Ar, and tolane–N2. The
results on tolane are consistent with a planar geometry for the species. They also provide information
about the symmetries of excited vibronic states in the species. The results on the van der Waals complexes
provide significant experimental constraints on where the small species bind to tolane. In addition, we
report the observation of a rapid excited‐state decay process in the complexes and discuss the possible
nature of this process.
Vibrational Relaxation of the 2ν5 Overtone of CDCl3 Following Tea CO2 Laser Excitation of the ν4 Mode
Authors: Vazquez M. A. , Azcárate M. L. , Quel E. J. , Doyennette L. , Rinaldi C. , Ferrero J. C.
Published: September 2007

The time variation of the 2ν5 fluorescence intensity was measured in CDCl3 excited in the ν4 C–D
bending mode by a TEA CO2 laser operating on the 10P(48) line. A fast rise of the fluorescence, with
a time constant ≤ 1 μs Torr, was first observed, showing that a fast equilibration of population occurs
between the ν4 and ν5 modes through a ν4 ↔ ν5 Coriolis‐assisted intermode transfer and a ν5 ↔ 2ν5
near‐resonant ladder‐climbing process. Then a first fast fluorescence decay was observed and attributed
to a (ν4, ν5) → ν2 intermode transfer with a rate constant of (7.10 ± 1.13)ms-1 Torr-1. At last, a much
slower decay, with a rate constant of 0.111 ± 0.015 ms-1 Torr-1, results from the less efficient intermode
transfer and V–T,R deexcitation processes involving the ν3 and ν6 states, and which compete to relax
the gas to a thermodynamic equilibrium.
Single Pulse Two‐Photon Laser‐Assisted Reduction of Benzophenone by Triethylamine to Form Excited Benzophenone Ketyl Radical
Authors: Figuera J. M. , Sastre R. , Costela A. , Garcia-Moreno I. , Al-Hakakk M. T. , Dabrio J.
Published: September 2007

The pulsed laser photolysis at 308 nm of the benzophenone‐triethylamine system in acetonitrile solution has been studied at room temperature. In the absence of triethylamine, phosphorescence emission of triplet benzophenone centred at 460 nm and with a lifetime of τ = 27 ± 1 μs is observed. Addition of triethylamine results in quenching of the benzophenone phosphorescence. Quenching rate constants KQ have been determined from emission intensifies and from experimental decay rate constants. The values KQ = (2.6 ± 0.3) × 109 M-1s-1 and KQ = (4.0 ± 0.5) × 109 M-1s-1, respectively, are obtained. On the addition of triethylamine, benzophenone phosphorescence diminishes and simultaneously a new emission with a fast decay rate and centred at 575 nm develops. This signal has been identified as emission from the excited benzophenone ketyl radical. A single pulse two‐photon absorption mechanism responsible of the emission at 575 nm has been identified and a kinetic model based on this mechanism has been developed. The model gives a satisfactory quantitative account of both our experimental results and those reported in the literature (quantum yield of radical formation and behaviour of the system as photoinitiator).
Rotationally Resolved Rate Constant Measurements for Removal of CH(A2Δ andB2∑−) by Ketene
Authors: Luque Jorge , Ruiz Javier , Martin Margarita
Published: September 2007

Rate constants for total removal of CH(A2Δ) and CH(B2∑−) in collisions with ketene were measured.
For the A2Δ state, rate constants increased with vibrational quantum number; measured values were
(4.5 ± 0.5) × 10-10 cm3 molec-1 s-1 and (8.0 ± 1) × 10-01 cm3 molec-1 s-1 for v′ = 0 and v′ = 2 respectively.
For v′ = 0, rotational levels with quantum numbers from N′ = 4 to N′ = 16 were removed
with similar rates within experimental errors; collisional disappearance of levels with higher rotational
quantum numbers was faster for a factor of about 1.4. Calculations of cross sections for ketene and
other fast colliders, assuming a multipole model, obtained a qualitative correlation with experimental
values. CH(B2∑−) was more efficiently removed than CH(A2Δ, v′ = 0); for the lowest rotational levels
a rate constant of (5.8 ± 0.3) × 10-10 cm3 molec-1 s-1 was measured and a moderate increase with
rotational quantum number was observed.