The Spectral Features of Polyatomic Molecules Multiphoton Excitation in a Strong IR‐Laser Field

Alimpiev, S. S.; Sartakov, Boris G.

doi:10.1155/lc.12.147

Cited by 9 publications

(9 citation statements)

References 7 publications

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“…As to the anharmonic constants G 33 and T 33 responsible for the splitting of the mode ν 3 , their values were taken to be G 33 ) 0.9262 cm -1 and T 33 ) -0.2487 cm -1 . 15 The values of the parameters of the function G(ν,E) finally used in solving equations (8) are presented in Table 2. When the absolute values of transition cross section (1) were calculated, the transition dipole moment µ 01 was taken at 0.388 D. 17 To allow for the possible contribution from the homogeneous broadening, Gaussian profile (2) was convolved with the Lorentzian profile It should be noted that this approach is approved, at least, in our case when expected IVR rates are much smaller than the width due to SIB.…”

Section: Computation Of Local Parametersmentioning

confidence: 99%

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment

et al. 1999

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The IR MP excitation spectra of the SF 6 molecule in the vibrational quasicontinuum (QC) measured experimentally in the vicinity of the ν 3 mode frequency are compared with their theoretical counterparts with a view to revealing the relative contribution from the statistical inhomogeneous broadening (SIB) and homogeneous broadening to the formation of the IR transition spectra in the QC. The IR MP spectra are found by solving rate equations, the cross sections of the successive transitions being calculated in the SIB approximation. The half-width γ L of the Lorentzian profile associated with the homogeneous broadening is the only adjustment parameter of the model. A good agreement (within the accuracy of measurement) is obtained between the experimental and theoretical IR MP spectra over a wide range of spectral and energy parameters. The γ L values are found which vary within the limits 0.53 e γ L e 10.2 cm -1 in the energy range 4500 e E e 30 000 cm -1 . The conclusion is drawn that the main parameters of the IR transition spectra in the QC (the position of the maximum, width, and intensity) are governed largely by the SIB effect, though the Lorentzian wings may play a decisive role when excitation occurs at the edges of the spectrum. The IR transition cross sections found are used to compute the IR MP excitation dynamics in the QC and determine the vibrational distribution function being formed. It is found that excitation in the QC may also give rise to a nonequilibrium bimodal distribution.

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Section: Computation Of Local Parametersmentioning

confidence: 99%

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment

et al. 1999

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“…The radia tive coupling within these multiplets renders the dressedstate model untractable for quantitative discussions, and cal culations should be based on the appropriate set of optical Bloch equations. Further discussions of multicolor multilevel excitation processes can be found elsewhere [9,30,31].…”

Section: B Two-color Excitationmentioning

confidence: 99%

Two-photon Rabi oscillations

et al. 1996

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Rabi oscillations reflect the existence of a coherent superposition of two molecular eigenstates during the interaction of molecules with a strong, resonant electromagnetic field. This phenomenon is not restricted to two-level systems. We demonstrate its occurrence in a three-level system where the radiation induces a two-photon absorption. The intermediate level is (slightly) detuned from resonance. For a theoretical descrip tion the dressed-state picture is adopted. The two-photon excitation is performed either by using one laser, yielding a one-color two-photon process, or by using two counterpropagating, spatially overlapping laser beams, yielding a two-color two-photon process. Rabi oscillations are produced by varying the fluence, i.e., by changing either the laser power or the molecule-laser interaction time. For the one-color case the two-photon transition dipole moment for an SF6 transition has been determined from the relation between laser fluence and number of Rabi oscillations.

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“…[3][4][5][6][7][8]. Rather than measuring the direct absorption of infrared photons, detection is instead based on changes in the chemical composition of the sample, which, for example, can be diagnosed from its mass spectrum.…”

Section: Introductionmentioning

confidence: 99%

“…Infrared resonance enhanced multiple photon dissociation (IRMPD) spectroscopy has proven to be a useful variant of action spectroscopy (see e.g. [3][4][5][6][7][8] ). Rather than measuring the direct absorption of infrared photons, detection is instead based on changes in the chemical composition of the sample, which, for example, can be diagnosed from its mass spectrum.…”

Section: Introductionmentioning

confidence: 99%

Infrared multiple photon dynamics and spectroscopy of cationic PABA and its dehydroxylated fragment ion

Moore

Meijer

Helden

2004

Phys. Chem. Chem. Phys.

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The gas-phase infrared spectra of cationic para-amino benzoic acid (PABA, H 2 N-C 6 H 4 -COOH) and its dehydroxylated fragment ion, the para-amino benzoyl (PABz, H 2 N-C 6 H 4 -CO) cation, are presented in the 500-2500 cm À1 range. The spectra are obtained via mass-selective infrared multiple photon dissociation (IRMPD) using a continuously tunable free electron laser. Although both spectra are in good overall agreement with results from density functional theory, some interesting discrepancies are also observed. Particularly in the spectrum of the PABz cation, the strongly anharmonic NH 2 out-of-plane bending mode causes substantial deviations from theory. The relative intensity of this out-of-plane bending mode in both the PABA and PABz cation spectra is much lower than calculated, similar to what has been reported for cationic aniline. For the PABz cation, two distinct fragmentation products are observed and recording the infrared spectra on these individual decay channels yields information on the dissociation mechanism. Moreover, it is experimentally shown that the decay rate into the two competing channels can qualitatively be described using statistical models.

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The Spectral Features of Polyatomic Molecules Multiphoton Excitation in a Strong IR‐Laser Field

Cited by 9 publications

References 7 publications

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment

Two-photon Rabi oscillations

Infrared multiple photon dynamics and spectroscopy of cationic PABA and its dehydroxylated fragment ion

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The Spectral Features of Polyatomic Molecules Multiphoton Excitation in a Strong IR‐Laser Field

Cited by 9 publications

References 7 publications

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF6. 2. Theoretical Simulation and Comparison with Experiment

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF6. 2. Theoretical Simulation and Comparison with Experiment

Two-photon Rabi oscillations

Infrared multiple photon dynamics and spectroscopy of cationic PABA and its dehydroxylated fragment ion

Contact Info

Product

Resources

About

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment

Transition Spectra in the Vibrational Quasicontinuum of Polyatomic Molecules. IR Multiple-Photon Absorption in SF₆. 2. Theoretical Simulation and Comparison with Experiment