Coherent anti-Stokes Raman spectroscopy study of the energy partitioning in the sodium(3P)-hydrogen collision pair with red wing excitation

Abstract

Figure 4. The adiabatic potentials corresponding to the model calculations: -, ( 3/2);- --, ( 1/2); and---, ( 1/2), the quantum numbers referring to the rotating frame; from left to right: low e, normal <, and high t case. close-lying potentials, i.e. for le and ne, lead to small differences in the channel energies and hence the wavenumbers of their nuclear wave functions are very similar. This leads to very efficient coupling of all three channels both in W+ and W". In the he case in each of these interaction matrices the first channel, referring to j = 1 /2, decouples very effectively from the other two with j = 3/2 due to the great difference in the channel energies. Carrying this line of arguments further, we set the corresponding coupling terms equal to zero and diagonalize the remaining 2X2 matrices. The resulting adiabatic potentials are not exactly but approxi-mately equal to the potential for + and the potential for ' in agreement with our calculated results. VII. SummaryThe measurement of total differential cross sections for the scattering of oriented alkali 2P3/2 atoms from ground-state, i.e., spherically symmetric, rare gas atoms shows a left/right asymmetry, if the initial state is chosen with m¡ = +3/2 or m¡ = -3/2 and the quantization axis is perpendicular to the scattering plane.The basics of this experimentally observed effect are discussed in detail in our report. First we have shown this feature to be qualitatively due to the fact that the two initial states refer, each exclusively, to the two parity sets of the corresponding interaction matrix. A closer look at the interaction matrix reveals that the centrifugal parts of the potentials with their different vector coupling coefficients are the only significant differences. A model calculation to reproduce the size of the asymmetry for various rare gas targets demonstrates that the decisive parameter for these variations is the ratio of spin-orbit and orbit-axis interaction.Finally we find from these calculations that orbital stereospecificity is indeed present in a certain case: namely the one with the spin-orbit interaction larger than the orbit-axis interaction at large internuclear separations.

CARS spectroscopy of the NaH2 collision complex: the nature of the Na(32 P)H2 exciplex — ab initio calculations and experimental results

“…3. Experimental setup of the CARS experiment A computer regulated time control was used to set a specific time delay between the FPD-laser and the CARS laser system which monitors the rovibronic state distribution of H2 at different times eg before, during and after the integration time of 1.5 gs where collision with Na(3 2p) and H2 occur [16].…”

“…We have applied CARS (Coherent Anti-Stokes Raman Scattering) [14] as an experimental technique to measure directly the internal state distribution of H2 after the quenching process in collision with Na(3ZP) [15,16]. With this method which we applied for the first time it is possible to measure the vibrational and rotational population in absolute quantity as well as the time dependence of the population and depopulation process.…”

Evolutionary algorithms and their application to optimal control studies

“…Further control experiments could entail manipulation of the rovibrational population distribution of the H 2 molecule after the collision, which could be detected by ns CARS [156,159,180], or opening the NaH formation channel. It should be noted that this (reactive) channel has already been observed in the above experiments ("laser snow") [181,182,192,193].…”

“…(c) Since only three atoms are involved in this reaction, with H 2 being the simplest conceivable molecule and sodium a hydrogen-like atom with only one outer shell electron, a theoretical simulation of the atom-molecule system with only three internal degrees of freedom is feasible [160,[163][164][165][166][167][168][169]. After excitation of the unbound (Na(3s)+H 2 ) system with a red-detuned laser pulse, a bound collision complex (Na(3p)+H 2 ) is formed (exciplex) with a well depth of 0.4 eV [159], due to the wave function overlap of the orbital of the H 2 molecule and the lobes of the valence electron of the Na(3p) atom [168]. The population of the excited state is reflected at the inner turning point of the well in the bound PES and oscillates in the well of the excited state.…”

New Dunham coefficients of the A 1 ∑ +-State of NaH and NaD

“…The Na#H collision system is prepared in a heat pipe oven filled with sodium and 100 mbar of hydrogen (n"1.2·10 cm\) and heated up to 600 K. A detailed description of the heat pipe oven is given elsewhere [24]. The sodium atoms in the gas phase (n"6·10 cm\) are excited in the 3p level by a flashlamp-pumped dye laser.…”