Some rotations like it hot: selective energy partitioning in the state resolved dynamics of collisions between CO2 and highly vibrationally excited pyrazine

Mullin, Amy S.; Park, Jeunghee; Chou, James; Flynn, George W.; Weston, Ralph E.

doi:10.1016/0301-0104(93)80228-2

Cited by 69 publications

(92 citation statements)

References 47 publications

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“…This approach was pioneered by Flynn and co-workers 10 who used transient infrared absorption of CO 2 and N 2 O following excitation through collisions with highly vibrationally excited NO 2 . Subsequent experiments have focused on the collisional deactivation of other highly excited donors, such as pyrazine [11][12][13][14] and hexafluorobenzene. 15 By choosing an energy-accepting molecule with well-resolved rotational and vibrational states such as CO 2 , individual energy transfer pathways can be identified and characterized.…”

Section: Introductionmentioning

confidence: 99%

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

Wall

Mullin

1998

The Journal of Chemical Physics

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The quenching of highly vibrationally excited pyrazine through collisions with CO2 is investigated as a function of initial pyrazine internal energy using a high-resolution laser transient absorption spectrometer. Experiments focus on energy exchanging collisions that result in excitation of rotations and translations in the ground vibrationless (0000) state of CO2. Highly vibrationally excited pyrazine (Evib=37 900 cm−1 or Evib=41 000 cm−1) is prepared via pulsed excitation at 266 nm or 246 nm, followed by rapid radiationless decay to the ground electronic state. The nascent CO2 rotational populations are measured by collecting the transient absorption of individual rovibrational lines at short times following the pyrazine excitation. The translational energies of CO2 recoiling from hot pyrazine are measured for numerous individual rotational levels. Energy dependent rate constants and probabilities are reported for both donor energies and results are compared with earlier studies using 248 nm excitation. These experiments reveal that for both donor energies, significant rotational and translational excitation of CO2 results from collisions with highly vibrationally excited pyrazine, as evidenced by the similarity in the observed rotational and translational distributions. Remarkably, however, the probabilities for the individual energy transfer pathways increase by as much as a factor of 3 for a 7% change in the pyrazine internal energy. The magnitudes and probabilities of energy transfer are described in terms of an energy transfer distribution function for the different donor molecule energies and implications for sequential quenching collisions are discussed.

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Section: Introductionmentioning

confidence: 99%

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

Wall

Mullin

1998

The Journal of Chemical Physics

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“…CO 2 line widths also vary nearly linearly with the final rotational angular momentum as was observed in other systems. 7,8,10,21,22 This near linear relationship, illustrated graphically in Figure 3, is an indication of a constant pyridine/ CO 2 effective impact parameter. 7,10 B.…”

Section: Resultsmentioning

confidence: 90%

Rotationally Resolved IR-Diode Laser Studies of Ground-State CO₂ Excited by Collisions with Vibrationally Excited Pyridine

et al. 2008

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Relaxation of highly vibrationally excited pyridine (C5NH5) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot pyridine (E' = 40,660 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Pyridine then collides with CO2, populating the high rotational CO2 states with large amounts of translational energy. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these CO2 rotational states. Doppler spectroscopy was used to measure the CO2 recoil velocity distribution for J = 58-80 of the 00(0)0 state. The energy-transfer distribution function, P(E,E'), from E' - E approximately 1300-7000 cm(-1) was obtained by re-sorting the state-indexed energy-transfer probabilities as a function of DeltaE. P(E,E') is fit to an exponential or biexponential function to determine the average energy transferred in a single collision between pyridine and CO2. Also obtained are fit parameters that can be compared to previously studied systems (pyrazine, C6F6, methylpyrazine, and pyrimidine/CO2). Although the rotational and translational temperatures that describe pyridine/CO2 energy transfer are similar to previous systems, the energy-transfer probabilities are much smaller. P(E,E') fit parameters for pyridine/CO2 and the four previously studied systems are compared to various donor molecular properties. Finally, P(E,E') is analyzed in the context of two models, one indicating that P(E,E') shape is primarily determined by the low-frequency out-of-plane donor vibrational modes, and the other that indicates that P(E,E') shape can be determined from how the donor molecule final density of states changes with DeltaE.

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“…These are collisions which exchange large quantities of energy in a single event. These were found experimentally [3][4][5][6][7] and in trajectory calculations. [8][9][10][11][12] They are defined as collisions which transfer a ∆E which is more than 5 times the value of the average energy transferred in a down collision 15 or 5 times the root mean square of the energy transferred per collision.…”

Section: B(e′) P(ee′) ) B(e) P(e′e)mentioning

confidence: 88%

Energy Transfer Rate Coefficients from Trajectory Calculations and Contributions of Supercollisions to Reactive Rate Coefficients

1996

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Quasiclassical trajectory calculations on the CS 2 -CO system were performed. Analytical biexponential functions were fit to the trajectory results, and energy-dependent energy transfer transition probability functions and rate coefficients were derived. They, in turn, were used in solutions of master equations. Unimolecular rate coefficients for cyclobutane fission and cyclobutene isomerization in Ar bath gas at various temperatures were obtained. Supercollisions, collisions which transfer more than 5 times the average energy transferred in a down collision, were found to contribute to the high-energy tail of the biexponential transition probability function. To assess their contribution to the unimolecular rate coefficients, their values which were obtained from trajectory-based double-exponential transition probabilities are compared with those obtained from singleexponential weak-collision transition probabilities. For cyclobutane fission an ∼5-fold increase in the value of the rate coefficient is found at 1000 K and ∼7-fold increase at 1500 K when the biexponential function is used. For cyclobutene isomerization the change ranges from an ∼7-fold increase at 500 K to an ∼9-fold increase at 1500 K. Since the magnitude of supercollisions and, thus, the magnitude of the tail of the probability distribution can vary depending on the system, a systematic study was performed on how the high-energy tail affects the values of the unimolecular rate coefficients. It was found that for weighing factors of the strongcollision contribution to the biexponential probability function of 0.5% or 10% of that of the weak-collision contribution (with an exponential parameter of 300 cm -1 ) the rate coefficient increases with the size of the strong-collision exponent and with temperature. When the contribution of the weak-collision exponent to the energy transfer probability function was artificially removed, it was found that in some cases, 0.5% of the strong-collision part contributes ∼70% to the overall rate coefficient while 99.5% of the weak-collision part contributes only 30%.

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Some rotations like it hot: selective energy partitioning in the state resolved dynamics of collisions between CO2 and highly vibrationally excited pyrazine

Cited by 69 publications

References 47 publications

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

Rotationally Resolved IR-Diode Laser Studies of Ground-State CO₂ Excited by Collisions with Vibrationally Excited Pyridine

Energy Transfer Rate Coefficients from Trajectory Calculations and Contributions of Supercollisions to Reactive Rate Coefficients

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Some rotations like it hot: selective energy partitioning in the state resolved dynamics of collisions between CO2 and highly vibrationally excited pyrazine

Cited by 69 publications

References 47 publications

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

“Supercollision” energy dependence: State-resolved energy transfer in collisions between highly vibrationally excited pyrazine (Evib=37 900 cm−1 and 40 900 cm−1) and CO2

Rotationally Resolved IR-Diode Laser Studies of Ground-State CO2 Excited by Collisions with Vibrationally Excited Pyridine

Energy Transfer Rate Coefficients from Trajectory Calculations and Contributions of Supercollisions to Reactive Rate Coefficients

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Rotationally Resolved IR-Diode Laser Studies of Ground-State CO₂ Excited by Collisions with Vibrationally Excited Pyridine