Vibrational population

Oxtoby D W 1981 Vibrational population relaxation in liquids Photoselective Chemistry Part 2 (Advances in Chemical Physics 47) ed J Jortner, R D Levine and S A Rise (New York Wiley) pp 487-519... 

Legay-Sommaire N and Legay F 1980 Observation of a strong vibrational population inversion by CO laser exoitation of pure solid oarbon monoxide IEEE J. Quantum Electron. 16 308-14... 

Jiang Y J and B G 1994 Vibrational population relaxation of perylene in its ground and exoited eleotronio states J. Phys. Chem. 98 9417-21... 

Moore P, Tokmakoff A, Keyes T and Payer M D 1995 The low frequenoy density of states and vibrational population dynamios of polyatomio moleoules in liquids J. Chem. Phys. 103 3325-34... 

Laubereau A., Fisher S. F., Spanner K., Kaiser W. Vibrational population lifetimes of polyatomic molecules in liquids. Chem. Phys. 31, 335-44 (1978). 

If the system under consideration is chemically inert, the laser excitation only induces heat, accompanied by density and pressure waves. The excitation can be in the visible spectral region, but infrared pumping is also possible. In the latter case, the times governing the delivery of heat to the liquid are those of vibrational population relaxation. They are very short, on the order of 1 ps this sort of excitation is thus impulsive. Contrary to a first impression, the physical reality is in fact quite subtle. The acoustic horizon, described in Section VC is at the center of the discussion [18, 19]. As laser-induced perturbations cannot propagate faster than sound, thermal expansion is delayed at short times. The physicochemical consequences of this delay are still entirely unknown. The liquids submitted to investigation are water and methanol. 

Habermann, R. (1976) Mathematical Models Mechanical Vibration, Population Dynamics and Traffic Flow, Prentice-Hall. 

In order to obtain the vibrational populations, Gaussian functions were fitted to each vibrational peak and then integrated to determine the relative population of that peak relative to the whole curve. We recognize that the Gaussians sometimes do not accurately represent the vibrational populations due to the tail on the high energy side of the vibrational peak... 

Table 1. Vibrational populations of 02(1AS) from the photodissociation of ozone with light of wavelength A.

It should also be mentioned that a theoretical model using an empirical LEPS potential energy surface has successfully been used to reproduce the vibrational population distribution of the products of this surface reaction.40 This approach confines itself to the assumptions of the Born-Oppenheimer approximation and underscores one of the major questions remaining in this field do we just need better Born Oppenheimer potential surfaces or do we need a different theoretical approach ... 

Luntz and co-workers have recently carried out an impressive study that follows in the spirit of the Eley-Rideal work.44 Specifically, laser-assisted recombination of N-atoms desorbing to form gas-phase N2 on Ru(0001) was investigated. Experimental measurements of state-selectively detected N2 recoiling from the surface recombination event were obtained using resonance enhanced multiphoton ionization and ion time-of-flight methods. In this way translational energy distributions of individual rovibrational states could be obtained experimentally. In addition, N2-vibrational population distributions could be derived. 

Fig. 3. Vibrational population distributions of N2 formed in associative desorption of N-atoms from ruthenium, (a) Predictions of a classical trajectory based theory adhering to the Born-Oppenheimer approximation, (b) Predictions of a molecular dynamics with electron friction theory taking into account interactions of the reacting molecule with the electron bath, (c) Born—Oppenheimer potential energy surface, (d) Experimentally-observed distribution. The qualitative failure of the electronically adiabatic approach provides some of the best available evidence that chemical reactions at metal surfaces are subject to strong electronically nonadiabatic influences. (See Refs. 44 and 45.)...

The scattered vibrational population distribution is remarkable. First of all, only a small fraction of the prepared population remains in the initial vibrational state, indicating that the survival probability is at most a few percent. At this low incidence energy, similar experiments carried out with NO(r = 2) scattering from Au(lll) were unable to detect vibrationally-inelastic processes, that is the vibrational survival probability is near unity.33... 

In the secular approximation [89], we can eliminate the coherence terms [e.g., pr, (x)(u / u")] in Eq. (III.9) such that the only diagonal terms contribute to the vibrational transitions through which the vibrational populations in various states are coupled. By applying the ladder model [89] to the interaction between the vibrational and heat-bath modes, the vibrational population decay constant is expressed as... 

The first term in Eq. (III. 10) is originated from the decay from v to v 1, while the second one, with the Boltzmann factor, is due to the thermally activated transition from v to v + 1. The vibrational population transfer, on the other hand, is only allowed to undergo the v —> v 1 transitions in the ladder model. Thus, the rate constant of the transfer is given by... 

The first investigations about the possibility of obtaining con-tinously vibrational population inversion in reaction products from the reactions... 

Maier JP, Seihneier A, Laubereau A, Kaiser W (1977) Ultrashort vibrational population lifetime of large polyatomic-molecules in vapor-phase. Chem Phys Lett 46 527 Shank CV, Ippen EP, Teschke O (1977) Sub-picosecond relaxation of large organic-molecules in solution. Chem Phys Lett 45 291... 

The calculations presented in the previous sections ignore the influence of molecular rotation on the efficiency of vibrational population transfer. This approximation defines useful models that permit qualitative investigation of the influence of background states on the efficiency of energy transfer within an embedded subset of states but is inadequate for the quantitative description of energy transfer in the corresponding real molecules. We expect the rotation... 

S. Masuda and S. A. Rice. Selective vibrational population transfer using combined STIRAP and counter-diabatic fields. J. Phys. Chem. C, (2014), DOI 10.1021/jp507923s. 

One major focus of these experiments has been the excited OH vibration population lifetime. This is currently interpreted as being dominated by either vibrational predissociation [2], i.e. the breaking of the hydrogen bond of an excited OH stretch [9], or by vibrational relaxation of the excited OH without such IR-induced bond breaking [7,10,11] (see Ref. 12 for a recent review). 

R. Rey, K.B. Mpller, J.T. Hynes, Ultrafast Vibrational Population Dynamics of Water and Related Systems A Theoretical Perspective, to appear in Chem. Rev. (2004). 

V. Engel Prof. Neusser, you mentioned the technique of Stimulated Raman Rapid Adiabatic Passage STIRAP, which allows for the coherent transfer of vibrational population selectively. Is the technique not another very efficient and experimentally verified scheme of coherent control ... 

The dynamics of the O Dj) + H2S -> OH(t/) + HS reaction have recently been investigated. Time-resolved spectra at 0.4 cm-1 resolution were recorded at 40-/rs intervals, beginning at 20 fj.s and continuing until 540 fis after the laser pulse. The time-dependent OH vibrational populations recorded in this experiment are shown in Figure 15. The rotational distributions in all vibrational levels at all observation times could be fitted by near room-temperature Boltzmann distributions. The vibrational distribution obtained at the earliest time (corresponding to approximately two gas-kinetic collisions after the reaction) was strongly inverted [45]. The LIF measurements... 

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