Femtosecond CARS on molecules exhibiting ring puckering vibration in gas and liquid phase

Scaria, A.; Konradi, J.; Namboodiri, V.; Sackmann, M.; Materny, A.

doi:10.1016/j.cplett.2006.11.017

Cited by 8 publications

(1 citation statement)

References 29 publications

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“…Conformation of small heterocyclic ring compounds such as containing nitrogen and sulfur atoms is of fundamental importance because these molecules often constitute a backbone of larger molecules of biological interest. − Because biological activities in many cases depend strongly on their molecular conformations, determination and identification of the molecular conformations on a designated electronic state is one of the essential goals of chemical and biological studies. , The conformation change arises from vibrational motion associated with ring deformation such as the ring puckering, and hence spectroscopic studies of this floppy, ring-puckering low-frequency vibrational mode should thoroughly be carried out. − The spectra of the heterocyclic molecules including four-, five-, and six-membered rings were measured by far-infrared and Raman spectroscopy and interpreted taking advantage of quantum-chemical calculations. , Vibrational energies and wave functions of the molecule on the ground electronic state were calculated with quartic and quadratic double-well potentials along the puckering coordinates, from which the peaks observed in the spectra were successfully identified. The potential parameters in vibrational potential surfaces of the ring-puckering motion obtained from spectral analyses provide crucial information on the molecular conformations, interconversion barrier between different structures, and forces responsible for the conformational change.…”

Section: Introductionmentioning

confidence: 99%

Observation of the Ring-Puckering Vibrational Mode in Thietane Cation

et al. 2017

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We have measured the high-resolution vibrational spectra of a thietane (trimethylene sulfide) cation in the gas phase by employing the vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopic technique. Peaks in the low-frequency region of the observed MATI spectrum of thietane originate from a progression of the ring-puckering vibrational mode (typical in small heterocyclic molecules), which is successfully reproduced by quantum-chemical calculations with 1D symmetric double-well potentials along the ring puckering coordinates on both the S and D states, the ground electronic states of neutral and cation of thietane, respectively. The values of the interconversion barrier and the ring-puckering angle on the S state, the parameters used for the quantum-chemical calculations, were assumed to be 274 cm and 26°. The barrier and the angle on the D state, however, are found to be 48.0 cm and 18.2°, respectively, where such small barrier height and puckering angle for the cation suggest that the conformation of thietane cation on the D state should be more planar than that of the thietane neutral.

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Section: Introductionmentioning

confidence: 99%

Observation of the Ring-Puckering Vibrational Mode in Thietane Cation

et al. 2017

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A comparison of the selective excitation of molecular modes in gas and liquid phase using femtosecond pulse shaping

Scaria

Konradi

Namboodiri

et al. 2008

J Raman Spectroscopy

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A feedback-controlled optimization in a femtosecond coherent-anti Stokes Raman scattering (CARS) process is applied to selectively excite or suppress vibrational modes in the gas and liquid phase. The optimal control experiments are performed on carbon disulfide and toluene molecules. Here our aim is to understand whether the interaction of the molecules with the surrounding medium affects the optimization process. The CARS excitation was chosen to be not in resonance with an electronic transition in the molecule but to excite different vibrational modes coherently. A pure phase modulation of the Stokes pulse resulted in changes of the ratio of the Raman lines observed in the nonlinear scattering spectrum. This could also be achieved when no temporal shift between the pump and Stokes laser resulted in a simple change of the Raman resonances. The relative intensities of the Raman lines could be changed more effectively in the liquid phase than in the gas phase. The higher density in the condensed matter, which hinders free rotation and makes interactions between molecules an important factor, obviously seems to influence the control mechanism.

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