Cation spectroscopy of 3,4-difluoroaniline by two-color resonant two-photon mass-analyzed threshold ionization

Resonant two-photon mass-analyzed threshold ionization of 2,5-difluoroaniline

“…The low-frequency mode X mainly involves the out-of-plane C-F bending vibration. Similar observations have been reported for 2,4-difluoroaniline and 3,4-difluoroaniline, whose vibronic features appear at 87 and 138 cm À1 , respectively [29,30]. Mode 1 denotes the breathing motion and mode 18a stands for the inplane CH bending vibration.…”

“…As reported in previous studies [29,30], the sum of the dE 1 's of 2-fluoroaniline and 4-fluoroaniline is À823 cm À1 [=554 + (À1377) cm À1 ], which differs from dE 1 of 2,4-difluoroaniline (À735 cm À1 ) only by 88 cm À1 . Similarly, the sum of the dE 1 's of 3-fluoroaniline and 4-fluoroaniline is À792 cm À1 [=585 + (À1377) cm À1 ], which differs from dE 1 of 3,4-difluoroaniline (À764 cm À1 ) only by 28 cm À1 .…”

“…The spectral assignment is achieved by comparing the present results with the experimental data of aniline [22,23], 2-fluoroaniline [24], 3-fluoroaniline [25], 2,4-difluoroaniline [29], and 3,4-difluoroaniline [30], as well as the predicted values from the TD-B3LYP/6À311++G(d,p) calculations. The normal vibrations can be viewed by following the GAUSSVIEW procedure of the GAUSSIAN 09 program [27].…”

“…Frequencies of the breathing motion (mode 1) are measured to be 798, 719, 712, 774, 695, 730, and 712 cm À1 for aniline, 2-fluoroaniline, 3-fluo- [22][23][24][25][26]29,30]. These data show that fluorine substitution can cause a decrease in the vibrational frequency of aniline.…”

“…The transition related to the out-of-plane NH 2 wagging (or called inversion) motion of 2,5-difluoroaniline appears at 695 cm À1 . The corresponding I 2 0 transitions of 2-fluoroaniline, 3-fluoroaniline, 4-fluoroaniline, 2,4-difluoroaniline, and 3,4-difluoroaniline have been reported with frequencies of 765, 754, 748, 783 and 756 cm À1 , respectively [24][25][26]29,30].…”