Photolysis wavelength dependence of the translational anisotropy and the angular momentum polarization of O 2 ( a Δ g 1 ) formed from the UV photodissociation of O 3The energy distribution, angular distribution, and alignment of the O ( 1 D 2 ) fragment from the photodissociation of ozone between 235 and 305 nm Resonance-enhanced multiphoton ionization coupled with time-of-flight product imaging has been used to study the O 3 (X 1 A 1 )ϩh→O(2p 3 P J )ϩO 2 (X 3 ⌺ g Ϫ ) product channel in the UV ͑ultraviolet͒ photodissociation of ozone at photolysis wavelengths of 226, 230, 233, 234, 240, and 266 nm. These imaging experiments, together with a measurement of the branching ratio into the different spin orbit states of the O atom, allowed the determination of the yields of the O 2 product in vibrational states greater than or equal to 26 as a function of wavelength. It was found that at 226, 230, 233, 234, and 240 nm, the yield was 11.8Ϯ1.9%, 11.5Ϯ1.2%, 8.2Ϯ2.0%, 4.7Ϯ1.8%, and 0.6Ϯ0.1%, respectively.
Resonance-enhanced multiphoton ionization coupled with
time-of-flight product imaging has been used to
study the
O2(3Σg
-) +
O(3P
j
) product channel in the UV
photodissociation of ozone at photolysis wavelengths
of 226, 230, 240, and 266 nm. For dissociation at 226 and 230 nm
the O(3P2) fragment is produced with
a
strongly bimodal velocity distribution, in keeping with the previous
findings of Miller et al., Syage, and
Stranges et al. at photolysis wavelengths of 226 and 193 nm.
At the longer dissociation wavelengths of 240
and 266 nm, the bimodal velocity distribution becomes less evident in
the O(3P2) product.
Anisotropy
parameters have been determined as a function of the
O(3P2) fragment speed. A very similar and
clear speed
dependence is evident at all photolysis wavelengths considered, with
the anisotropy parameters rising steadily
as the oxygen atom speed increases. The UV dissociation dynamics
of ozone to the channel producing triplet
products are discussed in light of this analysis.
We present measurements of the state-to-state differential scattering cross section (DCS) for X 1 + g Na 2 with Xe using a new sub-Doppler spectroscopic method and compare results with those obtained using molecular beam techniques on the same system; the agreement is good. Criteria for comparison are based on the recent finding (McCaffery A J and Wilson R J 1996 Phys. Rev. Lett. 77 48) that simple quasiclassical vector relations determine the direction of the initial relative velocity vector and the scattering angle. The incident velocity direction is such that the perpendicular component just opens the inelastic channel and the parallel component is scattered. The relationship is Newtonian but is modified by the molecule's characteristic quantum structure. Angular distributions from a range of experiments are found to obey the vector relation, suggesting that atom-molecule collisions are controlled by a quantum-modified Newtonian mechanics, the modification arising as a consequence of the internal energy level structure of the molecule. We introduce the term quantum-constrained kinematics to describe the hybrid mechanics and suggest that this may also influence other collisional events.
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