Direct observation of vibrational relaxation in highly excited HCN

Huang, Renfang; Wu, Jisen; Gong, Ming; Saury, Alain; M, Edwin Carrasquillo

doi:10.1016/0009-2614(93)e1271-h

Cited by 12 publications

(5 citation statements)

References 26 publications

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“…Self-relaxation, for example, mostly in collisions with vibrationless HCN molecules because of the low efficiency of overtone vibration excitation, should facilitate large quantum changes for the energized molecules because of the permanent dipole moment of HCN. Indeed, this has been shown previously in state-to-state collisional relaxation studies. , Population transfer between weakly coupled states, such as the 2:3 CH to CN resonance, the 1:3 CN to bend resonance, and the 1:1 CH to CN resonance appearing at high energy 33 could, as shown in at least one case for HCN, be enhanced in collisions with other HCN molecules. These expectations are consistent with the fact that the states populated and detected in the present experiments involve the exchange of many CH quanta for bending and CN stretching quanta.…”

Section: Discussionsupporting

confidence: 68%

“…Indeed, this has been shown previously in state-to-state collisional relaxation studies. 20,31 Population transfer between weakly coupled states, such as the 2:3 CH to CN resonance, 32 the 1:3 CN to bend resonance, 17 and the 1:1 CH to CN resonance appearing at high energy 33 could, as shown in at least one case for HCN, 20 be enhanced in collisions with other HCN molecules. These expectations are consistent with the fact that the states populated and detected in the present experiments involve the exchange of many CH quanta for bending and CN stretching quanta.…”

Section: Discussionmentioning

confidence: 99%

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Collision-Assisted Spectroscopy of HCN above the Isomerization Barrier

et al. 2003

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Double-resonance spectroscopy, using collisional energy transfer to populate high-lying vibrational states, reveals the location of 27 previously undetected levels in the ground electronic state of HCN. Three laserpumped overtones, (0,0 0 ,4), (0,0 0 ,5), and (1,0 0 ,5) provide the doorway through which to collisionally populate vibrational levels lying between 10330 and 17650 cm -1 . This greatly increases the energy range over previous studies using collision-assisted spectroscopy and provides access to states which have internal energy above the predicted isomerization barrier. Levels populated by collisions from (0,0 0 ,4) and (0,0 0 ,5) are detected directly via A ˜state fluorescence, while those from (1,0 0 ,5) are detected through resonant multiphoton dissociation resulting in CN (BfX) fluorescence. Although potentially, collision-assisted spectroscopy above the isomerization barrier could access HNC localized states, such states have not been identified in the present experiments.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Collision-Assisted Spectroscopy of HCN above the Isomerization Barrier

et al. 2003

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“…Quantum state resolved experiments on highly vibrationally excited molecules have followed two important trails, blazed by the two laser-based methods: overtone and stimulated emission pumping , (SEP). The thriving field of overtone spectroscopy and dynamics, ,− which is built entirely upon harmonically forbidden transitions, is testament to the amazing times in which we live. High spectral brightness lasers in the infrared and visible force one to consider carefully the meaning of the phrase “forbidden transition”.…”

Section: Quantum State Resolved Energy Transfer In Highly Vibrational...mentioning

confidence: 99%

“…There are, however, a number of molecules that are clearly tractable. One of these is HCN, and there has been some work done using overtone pumping. − Eventually one must come to grips with the fact that larger molecules have complex spectra that cannot be easily assigned. It remains a fascinating challenge for the future to see what can be learned about the collisional properties of such molecules.…”

Section: Quantum State Resolved Energy Transfer In Highly Vibrational...mentioning

confidence: 99%

Vibrational Energy Transfer

1996

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Many aspects of the collision dynamics of vibrational energy transfer are presented. Special emphasis is placed on three broad areas within this field: (1) vibrational energy transfer in large molecules (>10 modes) at low excitation, (2) vibrational energy transfer in large molecules at high vibrational excitation, and (3) vibrational energy transfer of highly excited small molecules. Advances in laser methods have revolutionized experimental investigations of all of these areas. Recent results are presented, and directions for the future are discussed.

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“…Trot (K) to molecules such as water and ammonia [45]. The energy relaxation mechanisms in HCN involve fast dissipation of vibrational energy as heat in a form of translational motion and rotational excitation (i.e.…”

Section: Non-thermal Population Of Rovibrational Levels Of Hcnmentioning

confidence: 99%

Precision spectroscopy of non-thermal molecular plasmas using mid-infrared optical frequency comb Fourier transform spectroscopy

Sadiek,

Puth,

Kowzan

et al. 2024

Plasma Sources Sci. Technol.

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Non-thermal molecular plasmas play a crucial role in numerous industrial processes and hold significant potential for driving essential chemical transformations. Accurate information about the molecular composition of the plasmas and the distribution of populations among quantum states is essential for understanding and optimizing plasma processes. Here, we apply a mid-infrared frequency comb-based Fourier transform spectrometer to measure high-resolution spectra of plasmas containing hydrogen, nitrogen, and a carbon source in the 2800 – 3400 cm–1 range. The spectrally broadband and high-resolution capabilities of this technique enable quantum-state-resolved spectroscopy of multiple plasma-generated species simultaneously, including CH4, C2H2, C2H6, NH3, and HCN, providing detailed information beyond the limitations of current methods. Using a line-by-line fitting approach, we analyzed 548 resolved transitions across five vibrational bands of plasma-generated HCN. The results indicate a significant non-thermal distribution of the populations among the quantum states, with distinct temperatures observed for lower and higher rotational quantum numbers, with a temperature difference of about 62 K. Broadband state-resolved-spectroscopy via comb-based methods provides unprecedented fundamental insights into the non-thermal nature of molecular plasmas – a detailed picture that has never been accomplished before for such complex non-thermal environment.

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Direct observation of vibrational relaxation in highly excited HCN

Cited by 12 publications

References 26 publications

Collision-Assisted Spectroscopy of HCN above the Isomerization Barrier

Collision-Assisted Spectroscopy of HCN above the Isomerization Barrier

Vibrational Energy Transfer

Precision spectroscopy of non-thermal molecular plasmas using mid-infrared optical frequency comb Fourier transform spectroscopy

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