High-power I2 laser in the 342-nm band system

Bradford, R. S.; Ault, E. R.; Bhaumik, M. L.

doi:10.1063/1.88280

Cited by 36 publications

(4 citation statements)

References 3 publications

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“…A 0 transition. [18][19][20][48][49][50][51][52][53][54] Because of the D X excitation sources utilized-electric discharges, lamps with monochromators, ArF lasers-it was impossible to achieve single vibrational level resolution in the excitation of the D state. The measurements were performed under multiple-collision conditions and the kinetic analysis utilized a onelevel approximation.…”

Section: Introductionmentioning

confidence: 99%

Collision-induced non-adiabatic transitions between the ion-pair states of molecular iodine: A challenge for experiment and theory

Tscherbul

Buchachenko

Akopyan

et al. 2004

Phys. Chem. Chem. Phys.

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The ion-pair states of molecular iodine provide a unique system for studying the efficiency, selectivity, and mechanisms of collision-induced non-adiabatic transitions. Non-adiabatic transitions between the first-tier ion-pair states in collisions with molecular partners and rare gases are analyzed and discussed. The qualitative features of the rate constants and product state distributions under single collision conditions are summarized and interpreted in terms of appropriate theoretical approaches. Two mechanisms for the non-adiabatic transitions are clearly identified. The first, operative for collisions involving molecular partners possessing permanent or transition electrostatic moments, is highly selective. It connects the initially prepared level in the E 0 þ g electronic state with the near-resonant vibronic level of the D 0 þ u state with a minimum change of the total angular momentum. In an extreme quasi-resonant case when the gap between initial and final rovibronic level is less than 1 cm À1 , this mechanism has a giant cross section, 40 times that of a gas kinetic collision. An electrostatic model, which includes the coupling of the giant E-D transition dipole moment with a moment of the colliding partner and the semiclassical Born approximation, provides a plausible interpretation of this mechanism. A second mechanism is shown to govern collisions with rare gas atoms. It results in population of several ion-pair states and broad distributions over rovibronic levels. This mechanism is successfully interpreted by quantum scattering calculations based on the diatomics-in-molecule diabatic potential energy surfaces and coupling matrix elements. The calculations provide good agreement with experimental measurements and reveal different mechanisms for the population of different electronic states. Unexplained features of the non-adiabatic dynamics and directions of future work are outlined.

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Section: Introductionmentioning

confidence: 99%

Collision-induced non-adiabatic transitions between the ion-pair states of molecular iodine: A challenge for experiment and theory

Tscherbul

Buchachenko

Akopyan

et al. 2004

Phys. Chem. Chem. Phys.

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“…This has been studied for excimer laser emitters such as K r F and XeCI where vibrational relaxation and mixing of two ion-pair states, B(f~ = 1/2) and C(f~ = 3/2) determine the effective pumping rate into the low-lying vibrational levels of the B state which contribute most strongly to the laser transitions (see for example M o r g a n et al 1983, Kvaran et al 1988). Some years ago molecular iodine in high pressure buffer gas was found to lase at 342 nm by using electron beam excitation (Bradford et al 1975;Ewing and Brau 1975;Hays et al 1976), and by ArF laser pumping (Shaw et al 1980). The lasing is due to a transition from the lowest state, D'(2g), in a cluster of 6 ion-pair states (0~,u, lg,., 2g,.)…”

Section: Introductionmentioning

confidence: 99%

Mechanism of vibrational relaxation and intersystem crossing within excited ion-pair states of I2

Kvaran

Jónsdóttir

Thorgeirsson

1991

Proc. Indian Acad. Sci. (Chem. Sci.)

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Visible and ultraviolet fluorescence of I2, following excitation by ArF/193 nm excimer laser pulses, was recorded for different pressures of argon buffer gas in a flow system. Dispersed fluorescence spectra due to the transitions D'(2g) --, A'(2,) and D(0. + )--, X(0 + ) were analysed by inversion and spectral simulations. Thus vibrational distributions in the emitting states were obtained as a function of pressure to determine the mechanism of relaxation to populate the lowest quantum levels of the D' state, which are the emitting states in the iodine laser. Fast intersystem crossing is found to occur from initially populated vibrational levels of the D state to other ion-pair states correlating with the ground state ions, followed by rapid relaxation, involving both direct vibrational relaxation within individual states and intersystem crossing between states.

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“…McCusker and coworkers [1] ] and laser action was originally obtained using electron beam excitation [2][3][4]. The efficiency of the system was found however to be rather low and interest in it quickly diminished.…”

mentioning

confidence: 99%

“…VIa(2) presents the RKR curve and table VIb displays the molecular constants for the D' state. It should be men-…”

mentioning

confidence: 99%

Collisionally induced optical double resonance in I2 : rotational analysis of the D'(2g) - A'(2u) laser transition

1982

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The I2 D'(2g)-A'(2u) transition has been excited by collisionally induced optical double resonance. This system has been rotationally analysed for more than 50 vibrational levels of the A'(2u) state. The long range behaviour of the A' state has been studied. The dissociation energy of this state has been determined to be Dc = 2 505.7 ± 1.9 cm-1. The D' state has been identifed with the α state of King et al. (Chem. Phys. 56 (1981) 145). The energies of the D' and A' states have been determined relative to X 1∑g+(ν = 0, J = 0) to be T0 = 40 331.6 ± 1.6 cm-1 and To = 9 988.7 ± 1.6 cm-1, respectively. The mechanism of this double resonance is discussed. Efficient collisional transfer to the D' state is observed and helps to shed some light on the operation of the optically pumped I2 D'-A' laser

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High-power I2 laser in the 342-nm band system

Abstract: Strong laser emission was observed in the 342-nm I2 band system from an e-beam–excited mixture of Ar and CF3I (250 : 1) at a total pressure of 10 atm. Laser emission occurred simultaneously at 342.0, 342.3, 342.4, and 342.8 nm with a peak power of 3.6 MW in a 10-nsec (FWHM) pulse.

Cited by 36 publications

References 3 publications

Collision-induced non-adiabatic transitions between the ion-pair states of molecular iodine: A challenge for experiment and theory

Collision-induced non-adiabatic transitions between the ion-pair states of molecular iodine: A challenge for experiment and theory

Mechanism of vibrational relaxation and intersystem crossing within excited ion-pair states of I2

Collisionally induced optical double resonance in I2 : rotational analysis of the D'(2g) - A'(2u) laser transition

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