Temperature dependence of the emission spectra of o-, p- and m-fluorobenzaldehyde in the vapor phase: rotational isomers of o- and m-derivatives

Spectroscopy and dynamics of the excited singlet and triplet states of 2,3-, 2,4- and 2,5-difluorobenzaldehyde vapors

“…Perhaps, it might be possible to obtain sharp phosphorescence spectra for these molecules in a jet, but it is generally not easy to measure the dispersed phosphorescence emission in a jet. On the other hand, molecules such as benzaldehyde and fluorobenzaldehydes are known to exhibit comparatively sharp emission bands in the vapor phase [1,2].…”

“…We have recently shown for mono-substituted benzaldehydes that the rotational isomers are separable through the phosphorescence measurements and determined the absolute energy levels of the two rotational isomers of 3-fluorobenzaldehyde vapor in the ground and first excited triplet states by means of emission and infrared spectroscopy [2,3]. However, at present the emission and absorption spectral data are not available for 2,3-, 2,4-and 2,5-difluorobenzaldehyde vapors.…”

Fourier Transform Microwave Spectroscopic and ab Initio Study of the Rotamers of 2-Fluorobenzaldehyde and 3-Fluorobenzaldehyde

“…These differ in the orientation of the carbonyl bond of the formyl group when it is pointed toward (O- cis ) or away from (O- trans ) the fluorine substituent of the ring. The two rotamers have been identified by NMR, infrared, , and phosphorescence measurements. − From the IR spectrum of 2-FBD recorded in a cold Ar matrix, Itoh et al reported an intramolecular C–H···F hydrogen bond in the more stable O- trans rotamer on the basis of the observation of a blue shift in the C–H stretching frequency of the formyl group. Though counterintuitive that the C–H bond should shorten, this assignment was based on the earlier work of Pinchas , who investigated a series of ortho substituted benzaldehydes and attributed similar blue shifts to intramolecular hydrogen bonding.…”

Emission and absorption spectra of 2,3,4-, 2,3,5- and 2,4,5-trifluorobenzaldehyde vapors

“…Although aromatic carbonyl compounds such as acetophenone and benzophenone are known to exhibit phosphorescence in the static vapor phase, the observed emission spectra are broad at temperatures in the neighborhood of room temperature [1]. On the other hand, aromatic carbonyl compounds such as benzaldehyde and fluorobenzaldehydes are known to exhibit comparatively sharp emission bands in the vapor phase [1][2][3][4][5].…”

“…We have recently shown for mono-and di-substituted fluorobenzaldehydes that the rotational isomers are separable through the phosphorescence spectral measurements and determined the energy levels of the two rotational isomers for 3-fluorobenzaldehyde and 3,4-difluorobenzaldehyde vapors in the ground and first triplet excited states by means of emission and infrared spectroscopy [2][3][4][5]. However, at present no information is available for the emission and absorption spectral data of trifluorobenzaldehyde vapors.…”