Conformational structure of cationic tetrahydropyran by one-photon vacuum ultraviolet mass-analyzed threshold ionization spectroscopy

Abstract

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

Determination of the highest occupied molecular orbital and conformational structures of morpholine based on its conformer-specific photoionization dynamics

“…It was previously demonstrated that high-resolution vacuum ultraviolet mass-analyzed threshold ionization (HR VUV-MATI) spectroscopy using a one-photon scheme is effective for exploring the conformational structures of polyatomic molecules as well as their conformer-specific photoionization dynamics and the inducing cationic structure of the conformers. [14][15][16][17][18][19][20][21] In particular, the conformational structures of tetrahydrofuran and tetrahydrothiophene, which are saturated five-membered heterocyclic molecules, were investigated using the constructed potential energy surfaces (PESs) associated with the conformational changes. 14 The replacement of the methylene group in cyclopentane with a heteroatom such as oxygen or sulfur changes the conformational structure, in contrast to the case for cyclopentane.…”

Determination of highest occupied molecular orbital and cationic structures of cyclopentanone using high‐resolution vacuum ultraviolet mass‐analyzed threshold ionization mass spectrophotometry

“…14 In general, information about an HOMO can be obtained by examining the geometrical changes induced by ionization, which can be extracted from the vibrational spectrum of the corresponding cation using the Franck-Condon (FC) principle. Recently, VUV mass-analyzed threshold ionization (MATI) spectroscopic investigations of four-, 15,16 five-, 17,18 and sixmembered [19][20][21][22] heterocycles showed well-resolved vibrational peaks in the full vibrational energy range for the corresponding cations. These spectra mostly consisted of symmetry-allowed fundamental bands.…”

Identification of individual conformers in C4H6O isomers using conformer-specific vibrational spectroscopy

“…5,6 Subsequent investigations have revealed that molecules with a sufficiently low conformer interconversion barrier exist in conformational equilibrium even at low temperatures, [7][8][9] whereas conformers with a high interconversion barrier retain their original composition during cooling via supersonic expansion. [10][11][12] For the former case, identifying peaks that correspond to a specic conformer in measured vibrational spectra requires additional exploration of the vibrational temperature-dependent conformational population, which, in turn, depends on the constructed potential energy surfaces associated with conformational interconversion. Nevertheless, deciphering the contribution of each conformer in the congested vibrational spectrum of a polyatomic molecule is still immensely difficult because of the comparable force elds between the atoms in conformers.…”