Articles you may be interested inAlignment of CN from 248 nm photolysis of ICN: A new model of the à continuum dissociation dynamics J. Chem. Phys. 87, 303 (1987); 10.1063/1.453627 NCNO→CN+NO: Complete NO(E,V,R) and CN(V,R) nascent population distributions from wellcharacterized monoenergetic unimolecular reactions J. Chem. Phys. 83, 5573 (1985); 10.1063/1.449680 Erratum: Nascent PO(X 2Π) E,V,R,T excitations from collisionfree IR laser photolysis: Specificity toward the PO(X 2Π1 / 2) spinorbit state [J. Chem. Phys. 8 2, 1376 (1985)] J. Chem. Phys. 83, 2003 (1985); 10.1063/1.449871 Nascent PO(X 2Π) E,V,R,T excitations from collisionfree IR laser photolysis: Specificity toward the PO(X 2Π1/2) spinorbit stateThe 266 nm photolysis of leN: Recoil velocity anisotropies and nascent E,V,R,T excitations for the eN + 1( 2P 3/2) and eN + 1(2P 1 / 2 ) channels a )We report the detection of nascent CN(X 2 ~ + ,v" = 0) following the 266 nm photodissociation of 300 K ICN, using sub-Doppler resolution laser-induced fluorescence, and polarized photolysis and probe lasers. When monitoring a particular CN internal state, the translational energies of the I + CN and 1* + CN channels differ by the iodine spin-orbit splitting 7603 cm -I. This is used to determine the separate contributions from each channel. For I + CN, high N" are selectively produced, with little population below N" = 20 (E ro !) = 3300 ± 300 cm -I), whereas the 1* + CN channel is associated with a distribution peaked sharply at low N "( (Ero!) = 355 ± 35 cm -I). It is clear that the low and high N" derive from linear and bent exit channel geometries, respectively. The spatial anisotropy is high (.81 = 1.3 ± 0.2;/31. = 1.6 ± 0.2) and initial excitation is via a parallel transition(s), probably to a state which begins correlating with 1* + CN in the linear configuration. Nascent spin-rotation states (FI and F 2 ) are also resolved for each channel, and for the case of I + CN, and FI and F2 populations are quite different. There is very little vibrational excitation ( < 2%), and the rotational distributions and translational energies of v" = 1 and 2 correspond to those of the I + CN channel. Subsequent to initial excitation, both adiabatic and/or nonadiabatic processes can ensure access to potential surfaces not excited directly, and a model is discussed which rationalizes the present experimental results, as well as the known variation of nascent E, V, R, T excitations with the photolysis wavelength.

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A survey of descriptive textbooks on musical acoustics shows a need for a legitimate, convincing explanation for the seemingly paradoxical behavior of the conical bore. We examine the differential equations and their solutions for spherically symmetric waves in three dimensions, settling on acoustic pressure as the variable of interest because it behaves more simply than particle velocity or displacement. Next we solve the boundary-value problem for all combinations of open and closed ends on truncated cones. The natural frequencies so obtained are then justified with plots of the pressure standing waves; it is at this point that we find a physically correct explanation that can be shared with students in a descriptive acoustics course. This pictorial approach is also used to explain the shapes of the input impedance curves for a straight pipe and a frustum. We conclude with a careful analysis of the successive distortions to which a pressure pulse is subjected as it bounces back and forth inside a frustum.