DOI: 10.5281/zenodo.7857371
title: Temperature-Dependent THz Properties and Emission of Organic Crystal BNA

description: This dataset is accompanying the paper "Temperature-Dependent THz Properties and Emission of Organic Crystal BNA" <strong>General data acquisition:</strong> The data was acquired with a modified Menlo Tera K-15 THz-TDS, consisting of a photoconductive emitter/receiver and four off-axis-parabolic mirrors (OAP). The second and third OAP, focusing and collecting the THz, are with a longer focus length to have enough space for the cryostat (Janis ST-100), which is equipped with 3 mm z-cut quartz windows for entry and exit of the THz beam. The delay line offers delays up to 1600 ps but the range was restricted to cut out the reflections from the z-cut quartz windows. Instead of averaging with Menlo’s own software ScanControl, each single trace is read out. 10 000 traces are saved for each unique measurement condition (crystal orientation, temperature) and saved in a single HDF-5 file. HDF-5 is an efficient (binary), cross-platform data format and can be read easily by i.e. Python or Matlab. <strong>The structure is as follows:</strong> <strong>raw_data </strong> The folder raw_data contains four folders. The folder “dark” contains a single file since this is independent of crystal orientation and temperature of the cryostat. For this measurement, the THz beam was blocked but all electronics, selected delay range etc. kept the same, to measure the noise-floor of the system. The folder reference was captured with the cryostat incl. windows, vacuum and crystal holder in place. Even though there should be no change in the transfer function by changing the temperature (due to the large aperture of the crystal holder), we still recorded reference traces for each temperature. The folder “BNA_orientation_001” contains the data with the organic crystal BNA in vertical orientation (&lt;001&gt;). The folder “BNA_orientation_100” contains the data with the organic crystal BNA in horizontal orientation (&lt;100&gt;). <strong>averaged_corrected_data</strong> The folder “averaged_corrected_data” reduces the large amount of raw data due to averaging. The program “Correct@TDS” (developed in the group of Dr. Romain Peretti, Terahertz Photonics Group @ IEMN - CNRS (UMR 8520), publication in preparation), is used to fit specific correction parameters for the delay, dilatation, amplitude noise and periodic sampling. The mean data is saved for each temperature in a text file called “mean.txt”. The other output of “Correct@TDS” is diagnostic information about the correction parameters and about the standard deviation in frequency- and time-domain. <strong>extracted_n_alpha</strong> The folder “extracted_n_alpha” contains the refractive index, absorption coefficient and more in a single HDF-5 file, extracted by the program phoeniks (https://github.com/TimVog/phoeniks), which is developed in our group. All results for the paper are saved in the internal folder structure of the HDF-5 file (for crystal orientation and temperature). The folder “nelly” shows the extraction of n and alpha done with Nelly [1] (https://github.com/YaleTHz/nelly) for the vertical orientation, which was used for the supplementary document. [1] Nelly: A User-Friendly and Open-Source Implementation of Tree-Based Complex Refractive Index Analysis for Terahertz Spectroscopy Uriel Tayvah, Jacob A. Spies, Jens Neu, and Charles A. Schmuttenmaer Analytical Chemistry 2021 93 (32), 11243-11250 DOI: 10.1021/acs.analchem.1c02132
description: This project was funded by the Deutsche Forschungsgemeinschaft (DFG) under Germany's Excellence Strategy - EXC 2033 - 390677874 – RESOLV and also under Project-ID 287022738 TRR 196 (SFB/TRR MARIE). These results are part of a project that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 805202 - Project Teraqua). The project "terahertz.NRW" is receiving funding from the programme "Netzwerke 2021", an initiative of the Ministry of Culture and Science of the State of Northrhine Westphalia. The sole responsibility for the content of this publication lies with the authors.