Branching ratio laser dependence

The branching ratios into the various 0(3Pj) states were surprisingly difficult to measure. The power dependence of the ionizing laser at the center of the Doppler profile was measured before each scan of the Doppler profile to provide proper normalization of the power dependence. It was found that the combination of our laser power and sample concentration put... 

The absorption spectrum, branching ratios, and final state distributions depend uniquely — at least in principle — on the initial quantum state of the parent molecule before it absorbs the photon. Recent experimental advances have made it possible to prepare with a first laser (wavelength Ai) the parent molecule in a particular state before a second laser (wavelength A2) dissociates it (Hausler, Andresen, and Schinke 1987 Vander Wal, Scott, and Crim 1991). This allows the study of molecular dynamics on a truly state-specific level. Incoherent averaging caused by the simultaneous dissociation of several initial states is thus avoided. The... 

The branching ratio of the photolysis products depends on the intensity of the IR laser pulse. Thus, at low intensities conversion to products is highly favored (efficiency of 88%) whereas at high intensities dissociation to reactants prevails (efficiency of 35%). By showing that 127 lies in a well between the entrance channel and a reaction barrier, these data provide direct evidence for a multiple-well potential energy surface. The significantly lower... 

The cross sections and the S( P2) S( f>2) branching ratios for processes 43 and 44 can be determined uniquely because process 44, which is linearly dependent on the photodissodation laser power, dominates at low F values, while process 43, which is proportional to the square of the photodissociation laser power, is expected to dominate at high F values. 

Two kinds of ion species are involved depending on their atomic level properties. One has two optical/peripheral electrons, such as A1+, In+, where the clock transition is based on a dipolar electric transition, and the other has only one optical electron, such as Ca+, Hg +, Sr+, and Yb+, for which the clock transition is based on either a quadrupolar or an octopolar dipole electric transition. With the first kind of ion, the cooling transition is cycling wherein 100% of the atoms relax to the lower level, while the cooling transition (nS to nP) of the second kind relaxes to two different-orbital lower levels the fundamental ( 5) and one metastable level ((n-1) D). The value of the relaxation branching ratio between the nS and metastable (n-1) D levels is such that a significant fraction of ions will populate the metastable (n-l)D level. Thus, another laser is required to pump the atomic ions from the (n-l)D level back to the optically excited state nP. 

Experiments with HCl (Park et al. 1991) have confirmed the predictions of coherent-control theory, particularly the sinusoidal dependence of the ionization rate on the relative phases of the two exciting lasers, as well as the dependence of the degree of sinusoidal modulation of the ionization cinrent on the relative laser field intensities. This technique was also used in experiments on controlfing the product ratio in the photodissociation of HI (Zhu et al. 1995) and the branching ratio in the photodissociation of Na2 (Shnitman et al. 1996). 

D. M. Brenner, Infrared multiphoton-induced chemistry of ethyl vinyl ether Dependence of branching ratio on laser pulse duration, Chem. Phys. Lett. 57 357 (1978). 

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