Rotational excitation II

The vector of the electromagnetic field defines a well specified direction in the laboratory frame relative to which all other vectors relevant in photodissociation can be measured. This includes the transition dipole moment, fi, the recoil velocity of the fragments, v, and the angular momentum vector of the products, j. Vector correlations in photodissociation contain a wealth of information about the symmetry of the excited electronic state as well as the dynamics of the fragmentation. Section 11.4 gives a short introduction. Finally, we elucidate in Section 11.5 the correlation between the rotational excitation of the products if the parent molecule breaks up into two diatomic fragments. 

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Kouri, D.J. (1979). Rotational excitation II Approximation methods, in Atom-Molecule Collision Theory, ed. R.B. Bernstein (Plenum Press, New York). 

See also the reviews by D. J. Kouri, Rotational excitation II Approximation methods, in Atom Molecule Collision Theory A Guide for the Experimentalist", R. B. Bernstein, ed., Plenum Press, New York (1979), p. 301, and H. Rabitz, Effective Hamiltonians in molecular collisions, in "Dynamics of Molecular Collisions, Part B", W. H. Miller, ed., Plenum Press, New York (1976), p. 33. 

In addition to the processes just discussed that yield vibrationally and rotationally excited diatomic ions in the ground electronic state, vibrational and rotational excitations also accompany direct electronic excitation (see Section II.B.2.a) of diatomic ions as well as charge-transfer excitation of these species (see Section IV.A.l). Furthermore, direct vibrational excitation of ions and molecules can take place via charge transfer in symmetric ion molecule collisions, as the translational-to-internal-energy conversion is a sensitive function of energy defects and vibrational overlaps of the individual reactant systems.312-314... 

By using a time-of-flight method to distinguish between the C, C2 and C3 components of a thermal (2550 K) carbon beam, it was possible to measure the visible emission from the CN (B S ) product of the four-centre exchange reaction C2 + NO [614]. Vibrational states up to V = 4 are populated and can be fitted by a temperature of Tvib 6900 ( 700) K. The rotational excitation of the CN (B II ) decreases as the vibrational excitation increases (7000 > Trot 3500 K for 0information theory analysis of the data shows agreement of the experimental distributions with the prior forms. 

The latest experiments have used tunable laser induced fluorescence techniques to monitor the CN(A 2 ) fragments produced through photodissociation of ICN by a frequency quadrupled NdrYAG laser (X = 266.2 nm) or a flash lamp (X > 220 nm) ). They each concluded that virtually all the CN(JT) fragments are formed without vibrational excitation (Nj,=o-No= i > 1.00 0.02) but that they are rotationally excited with a distriTtution characterised approximately by a rotational temperature of 3000 K. While earlier time-of-fl ht photofragment spectroscopy experiments had been rationalised by assuming that CN(A 2 ) and CN(4 II)... 

The vacuum u.v, photodissociation of NO2 and NOCl was studied by Welge and Lenzi and Okabe, who observed fluorescence from vibrationally and/or strong rotationally excited NO in the and B II electronic states. The... 

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