Simultaneous non-invasive gas analysis in artificial photosynthesis reactions using rotational Raman spectroscopy

2022

Optimising reactions in artificial photosynthesis research requires screening of many reaction and operation parameters, which is often resource-intense and time-consuming. In this paper, we demonstrate the use of a rotational Raman-based spectrometer for non-invasive quantification of several gases (H2, O2, N2, CO, CO2) with short analysis times (15 s), enabling high throughput screening. Furthermore, with this device, reaction progress can be monitored in situ, by real-time simultaneous quantification of multiple gases. We have applied this instrument and developed a method to study the O2 dependency of a prototypic light-driven hydrogen evolution reaction, showcasing the value of this ap…

Raman spectroscopy of glycolic acid complexes with N2

2019

High overtone excitation induced conformational isomerization of glycolic acid – nitrogen complex in an argon matrix was investigated by Raman spectroscopy. The interaction between glycolic acid and nitrogen change the green light (532 nm) induced isomerization processes compared to non-complexed glycolic acid. The 180° rotation around of the Csingle bondC bond and stabilization of carboxyl Odouble bondCsingle bondOsingle bondH dihedral angle to trans position were the main conformational changes observed in the complex of the lowest energy conformer and nitrogen. Interestingly, only one stable light-induced conformational product was observed, which isomerises back to the lowest energy con…

High vibrational overtone excitation‐induced conformational isomerization of glycolic acid in solid argon matrix

2018

Electronic Absorption Spectra of HXeCl, HXeBr, HXeI, and HXeCN in Xe Matrix

2000

The electronic UV absorption spectra of thermal reaction products H−Xe−Y (Y= Cl, Br, I, or CN) have been measured in solid Xe at 12 K. The spectra are obtained after the annealing of an extensively...

Raman spectroscopy and high-overtone driven isomerization of glyoxylic acid in solid argon

2013

High-overtone induced chemistry of glyoxylic acid isolated in a low-temperature argon matrix was investigated using Raman spectroscopy. The Raman spectra of two most stable conformers of glyoxylic acid are presented. Upon excitation in high overtone vibrational bands by 532 nm irradiation of the lowest energy conformer most abundant in neat deposited sample, the isomerization of glyoxylic acid was observed. The process most plausible proceeds via absorption into the fifth vibrational overtone state of the OH group or its combination with the torsional vibrational transition. The assignment of the fundamental vibrational spectra was assisted by quantum chemical harmonic and anharmonic vibrat…

Electronic spectroscopy of I2–Xe complexes in solid Krypton

2012

In the present work, we have studied ion-pair states of matrix-isolated I(2) with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I(2)-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I(2) with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm(-1) from the X → D transition of I(2). Observed redshift can be explained by symmetry breaking of ion-pair states within the I(2)-Xe complex. Systematic Xe doping of Kr ma…

Photolysis of HCOOH monomer and dimer in solid argon: Raman characterization of in situ formed molecular complexes

2010

Raman spectroscopy combined with the matrix isolation technique was employed to study the 193-nm photodecomposition products of formic acid in an argon matrix. The Raman-active fundamentals belonging to the CO(2) + H(2) and CO + H(2)O photoproducts were assigned. Also, bands due to Fermi resonance between the stretching vibration (nu(1)) and the overtone of the bending mode (2nu(2)) of CO(2) were identified. Both ortho- and para-H(2) molecules were identified from their rotational lines S(0)(1) and S(0)(0), respectively. These bands appeared upon matrix annealing as well as after prolonged photolysis. Additionally, photolysis of FA dimers produces oxalic acid and its secondary photoproducts…

Conformational-Dependent Photodissociation of Glycolic Acid in an Argon Matrix

2023

Ultraviolet-induced photodissociation and photo-isomerization of the three most stable conformers (SSC, GAC, and AAT) of glycolic acid are investigated in a low-temperature solid argon matrix using FTIR spectroscopy and employing laser radiation with wavelengths of 212 nm, 226 nm, and 230 nm. The present work broadens the wavelength range of photochemical studies of glycolic acid, thus extending the understanding of the overall photochemistry of the compound. The proposed kinetic model for the photodissociation of glycolic acid proceeds from the lowest energy conformer (SSC). The model suggests that ultraviolet light induces isomerization only between the SSC and GAC conformers and between …

Vibrational Spectrum of HXeSH revisited : Combined computational and experimental study

2020

Vibrational spectrum of HXeSH embedded in low-temperature matrix is experimentally studied. To support the spectrum interpretation, anharmonic vibrational analysis is performed using different models and basis sets and the data is compared with previous experimental and theoretical analyses. Computations of overtones and combination modes allowed for new band assignments. The HXeSH molecule exhibits high anharmonicity similarly as other molecules from the noble-gas hydride family. Comparison of the employed computational methods shows once again that the modelling of the noble-gas compounds faces theoretical challenges to yield quantitatively reliable results. peerReviewed

Photodissociation of Formyl Fluoride in Rare Gas Matrixes

2006

Photodissociation of formyl fluoride (HCOF) is studied in Ar, Kr, and Xe matrixes at 248 and 193 nm excitation by following spectral changes in the infrared absorption spectra. In all matrixes, the main photodissociation products are CO/HF species, including CO-HF and OC-HF complexes and thermally unstable CO/HF species (a distorted CO/HF complex or a reaction intermediate), which indicate negligible cage exit of atoms produced via the C-F and C-H bond cleavage channels. However, the observation of traces of H, F, CO, CO(2), F(2)CO, FCO, and HRg(2)(+) (Rg = Kr or Xe) in Kr and Xe matrixes would imply some importance of other reaction channels too. The analysis of the decay curves of the pre…

Raman spectroscopy of acetic acid monomer and dimers isolated in solid argon

2011

Acetic acid (AA) monomer and its dimers were studied by means of Raman spectroscopy combined with the matrix isolation technique. All fundamental bands of CH3COOH monomer were identified, including the CH3 torsional mode. Additionally, three overtone or combination modes were observed as a result of their enhanced intensities by Fermi resonance (FR). Twenty bands of the cyclic dimer (C2h) were identified and assigned, among which appear all intermolecular modes. Bands due to two different higher energy forms of the dimer were also identified. The experimental assignments are supported by ab initio calculations. Copyright © 2011 John Wiley & Sons, Ltd.

UV laser induced photolysis of glycolic acid isolated in argon matrices

2021

The photochemistry of matrix-isolated glycolic acid, induced by UV light, was studied by FTIR spectroscopy and B3LYPD3/6-311++G(3df,3pd) calculations. Several decomposition pathways were found to take place upon 212 nm and 226 nm wavelengths irradiation. A number of complexes formed between photoproducts were identified, among them those of formaldehyde with water, carbon monoxide and carbon dioxide as well as the H2O-CO complexes. The structure and spectroscopic assignment of the photoproducts were made comparing the experimental results with the theoretical predictions and available literature data. The observed formation of different complexes indicates various pathways for their formati…

Raman spectroscopy of formic acid and its dimers isolated in low temperature argon matrices

2009

Raman spectroscopy combined with matrix isolation technique was employed to study formic acid monomer and its dimers. Nine fundamentals of the HCOOH monomer were identified. Additionally, the OH torsion overtone is observed and it is engaged in Fermi resonance with the δCOH mode. Several bands of the cyclic (C2h) dimer were identified and assigned. The less stable open form (Cs) of the dimer was also present in the experiment. Three intermolecular modes for the cyclic and one mode for the open dimer were found in the low frequency region. The experimental studies were supported by harmonic and anharmonic DFT calculations.

FTIR matrix isolation and theoretical studies of glycolic acid dimers

2018

Glycolic acid (GA) dimers were studied in low temperature argon matrices by means of FTIR spectroscopy. Experimentally, the dimers were produced when monomeric glycolic acid molecules were thermally mobilized upon annealing of argon matrices at 25–35 K. The experimental spectra observed upon annealing indicate the presence of three different dimer structures. Computationally, MP2 and DFT calculations were used to study the potential dimer species in order to scrutinize the possible dimer structures, their energetics and their spectral features. Altogether 27 local minima were found for dimer structures for the three lowest conformers of glycolic acid considered based on previous studies on …

Structure and Matrix Isolation Infrared Spectrum of Formyl Fluoride Dimer:  Blue-Shift of the C−H Stretching Frequency

2006

Infrared spectroscopy (IR) of formyl fluoride (HCOF) dimer is studied in low-temperature argon and krypton matrixes. New IR absorptions, ca. 17 cm(-1) blue shifted from the monomer C-H stretching fundamental, are assigned to the HCOF dimer. The MP2/6-311++G calculations were utilized to define structures and harmonic frequencies of various HCOF dimers. Among the four optimized structures, the dimer having two C-H...O hydrogen bonds possesses strongest intermolecular bonding. The calculated harmonic frequencies of this dimer structure are shifted from the monomer similarly as observed in the experiment. Thus, we suggest that the experimentally observed blue shifted C-H bands belong to the di…

Electronic spectroscopy of I2-Xe complexes in solid Krypton

2012

In the present work, we have studied ion-pair states of matrix-isolated I2 with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I2–Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I2 with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm−1 from the X → D transition of I2. Observed redshift can be explained by symmetry breaking of ion-pair states within the I2–Xe complex. Systematic Xe doping of Kr matrices shows…