Experiments explore the influence of different C-H stretching eigenstates CH3D on reaction with Cl(2P3/2). We prepare mid |110>|0>(A1,E), |200>|>0(E), and |100>|0> +nu3 +nu5 by direct midinfrared absorption near 6000 cm(-1). The vibrationally excited molecules react photolytic Cl atoms, we monitor vibrational states CH2D or CH3 radical products 2+1 resonance enhanced multiphoton ionization. Initial excitation |200>|0>(E) state leads to a twofold increase in ground compared to|100>|0>...

Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present high-resolution MATI spectrum demonstrated a much finer richer vibrational structure than that the previously reported two-photon spectrum. From photoionization efficiency curve, accurate energy ionic ground state was confidently...

Vibrational spectra in the ground electronic states, X̃ 2B1, of fluoro-, chloro-, bromo-, and iodobenzene cations excited B̃ 2B2, chloro- bromobenzene have been measured by mass-analyzed threshold ionization (MATI) via one-photon excitation with vacuum ultraviolet light. The consist mostly strong 0–0 bands fundamentals, overtones, combinations totally symmetric a1 modes. In particular, observed vibrational states assigned referring to assignments for ionic those neutral molecules. From MATI...

One-photon vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy was used to characterize the essential conformations of tetrahydrofuran (THF) and thus determine stereochemistry furanose ring constituting backbones DNA RNA. Since VUV-MATI spectrum THF exactly corresponds vibrational gas-phase cation, above cation detected using time-of-flight mass spectrometry featuring delayed pulsed-field target in high Rydberg states by scanning wavelength VUV pulse across region...

We have measured the high-resolution vibrational spectra of a thietane (trimethylene sulfide) cation in gas phase by employing vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopic technique. Peaks low-frequency region observed MATI spectrum originate from progression ring-puckering mode (typical small heterocyclic molecules), which is successfully reproduced quantum-chemical calculations with 1D symmetric double-well potentials along ring puckering coordinates on...

Vibrational spectra of p-, m-, and o-difluorobenzene cations in the ground electronic states have been measured by vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy. From MATI spectra, energies o-difluorobenzenes to ionic determined be 73 861±5, 75 332±5, 003±5 cm−1, respectively. A number vibrational modes, including fundamentals, their combinations, overtones were distinctly observed could assigned successfully comparing with results from density functional...

One-photon MATI spectra of phenylacetylene and benzonitrile were obtained by using vacuum ultraviolet radiation generated four-wave difference frequency mixing in Kr. Accurate ionization energies determined from the positions 0−0 bands, which are 8.8195 ± 0.0006 9.7288 eV, respectively. Vibrational frequencies molecular ions also. Assignments made utilizing symmetry selection rule Franck−Condon factors calculated at BP86, B3LYP, B3PW91 density functional theory levels with 6-311++G(2df,2pd)...

The vibrational spectrum of a pyrimidine cation in the ground electronic state was obtained using vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy. Accurate energy determined from 0–0 band position VUV-MATI and measured by varying PFI field to zero limit, which is 75 258 ± 7 cm−1 (9.3308 eV). displayed large number peaks, could be nearly completely assigned through Franck–Condon analysis performed with variations geometrical parameters at B3LYP/cc-pVTZ level....

The conformers of tetrahydrothiophene (THT) in the neutral (S0) and cationic (D0) ground states have attracted significant attention terms conformational interconversion through pseudorotation. Herein, these were explored by utilising one-photon mass-analysed threshold ionization (MATI) spectroscopy using coherently tunable vacuum ultraviolet laser pulse generated four-wave difference-frequency mixing Kr medium, which allowed acquisition vibrational spectrum corresponding cation. To identify...

Isobutanal is an aliphatic aldehyde which has been extensively studied as important intermediate in isomerization reactions well astrochemically relevant models the interstellar medium. Herein, we report on conformer-specific photoionization and conformational stabilities of isobutanal utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet (VUV) pulses. The population under different supersonic expansion conditions was explored to identify...

Surfaced-enhanced Raman scattering (SERS) of 4,4'-biphenyldithiol (BPDT) has been investigated at a silver island film. Ordinary (OR) spectra neat sample in solid state and basic solution have also taken for comparison. The spectral feature the SERS spectrum was similar to that OR solution, except broadening ring stretching bands indicative presence surface-phenyl <TEX>$\pi$</TEX> interaction. In contrast, only absence C-H band with very small cross-section seemed not pertinent judging...

Composition of the crotonaldehyde sample at ambient temperature was determined as 93.0%, 3.4%, and 0.2% for <italic>tt</italic>-/<italic>tc</italic>-/<italic>ct</italic>-/<italic>cc</italic>-conformers, respectively, first time.

We report conformational and vibrational assignments of vacuum ultraviolet mass-analyzed threshold ionization spectrum the isolated gauche conformer, based on previously determined conformer-specific photoionization stabilities isobutanal. The pure cationic conformer was acquired by removing trans via conformationally effective cooling with Ar carrier gas. peaks in were assigned Franck-Condon (FC) fitting adjusting geometrical parameters at CAM-B3LYP/cc-pVTZ level. Based good agreement...

Piperidine has received attention in pharmaceutical synthesis and biochemical degradation because of its conformational activity. We explored the structures piperidine neutral (S0) cationic (D0) ground states by conformer-specific vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy, which provides high-resolution vibrational spectra for corresponding conformer. To identify conformers to obtained VUV-MATI spectra, equilibrium S0 D0 were determined at various density...

Abstract The conformational structure of cyclopentanone (CP) and the photoionization dynamics corresponding conformer were investigated using high‐resolution vacuum ultraviolet mass‐analyzed threshold ionization (MATI) spectroscopic technique. To identify to measured MATI spectrum, potential energy surfaces associated with twisting carbonyl wagging motions in S 0 D states constructed at B3LYP/cc‐pVTZ level, where twisted both corresponded global minimum. Furthermore, Franck–Condon fitting...

Ion selectivity in a simple cyclic peptide nanotube, composed of four cyclo[-(D-Ala-Glu-D-Ala-Gln)<TEX>$_2-$</TEX>] units, is investigated by calculating the PMF profiles <TEX>$Na^+$</TEX>, <TEX>$K^+$</TEX>, and <TEX>$Cl^-$</TEX> ions permeating through nanotube water. The final obtained from umbrella sampling (US) method show an excellent agreement with those thermodynamic integration (TI) method. <TEX>$Na^+$</TEX> <TEX>$K^+$</TEX> display free energy wells while curve features barriers,...

Alkylpyrazines, which are well-known as aromatic substances and traditional medicines, interesting molecular systems, their methyl conformations result in unique structural dynamical properties.

Methyl vinyl ketone (MVK), a volatile compound with photochemical activity, has received considerable attention in the fields of environmental chemistry and atmospheric chemistry.

Isolating and identifying the conformational forms of molecules are imperative processes to investigate chemical reaction pathways individual conformers.

Conventional ion spectroscopy is inapplicable for ions produced in low concentrations or with spectral resolutions. Hence, we constructed a high-resolution vacuum ultraviolet mass-analyzed threshold ionization (HR VUV-MATI) spectrometer composed of four-wave frequency mixing cell capable generating long-lasting and intense VUV laser pulses ∼1 × 1010 photons/pulse at wavelengths 123.6-160.0 nm, space-focused linear time-of-flight photoionization chamber new ion-source assembly, compact...

Tetrahydrofuran (THF) has garnered significant attention due to its pivotal role in biological and chemical processes. The diverse array of conformations exhibited by THF profoundly impacts reactivity interactions with other molecules. Understanding these conformational preferences is crucial for comprehending molecular behavior. In this study, we utilize infrared (IR) resonant vacuum ultraviolet photoionization/mass-analyzed threshold ionization (VUV-PI/MATI) mass spectroscopies capture...

The surface-enhanced Raman scattering (SERS) intensities for ethanethiol adsorbed on a silver island film have been measured variety of annealing conditions over the 15−300 K temperature range. Reversible dependence C−S stretching an unannealed similar to case 1-propanethiol reported previously was found, with intensity at 15 being greater than that 300 by factor ∼2.5. preferential SERS enhancement lower surface temperature, normalized value K, decreased substantially as films were annealed....