A joint theoretical–experimental investigation of the lower bound states of the NO(X 2Π)–Ar complex

Abstract

In an extension of recent work [Y. Kim, K. Patton, J. Fleniken, and H. Meyer, Chem. Phys. Lett. 318, 522 (2000)], overtone pumping followed by resonantly enhanced multiphoton ionization (REMPI) detection is used to record spectra corresponding to excitation of the lowest five bend–stretch vibrational levels of the NO(X 2Π,v=2)–Ar complex. High-quality ab initio potential energy surfaces, coupled-electron-pair (CEPA) and coupled cluster single double triple [CCSD(T)], are used to predict the positions of these same five states, but in the NO(X 2Π,v=0)–Ar complex. The vibrational wave functions and basis set expansion coefficients, determined within the adiabatic bender model, are then used to simulate the observed spectrum for excitation of the NO(X 2Π, v=2)–Ar complex. The overall position and rotational substructure matches the experiment extremely well, particularly when the simulation is based on the presumably more accurate CCSD(T) potential energy surfaces.

The NO(X2Π)–Ne complex. II. Investigation of the lower bound states based on new potential energy surfaces

“…We followed our earlier 18,37,42,43 implementation of the distributed Gaussian method of Hamilton and Light. 44 All calculations were carried out with our Hibridon 4 code.…”

“…4͒. 18 The P-type doubling, also discussed in the preceding section, leads to an additional splitting of each curve ͑see Fig. 11 of Ref.…”

“…One can use a space-or body-frame expansion. 18 In a body-frame ͑BF͒ expansion we construct the complete wavefunction by first defining primitive-P functions, which are, in the coordinate representation,…”

“…Alternative choices for the BF basis in which to expand the total wavefunction have been discussed previously. 18 We expand the full wavefunction in this signed-P BF basis ͓Eq. ͑4͔͒.…”

“…In the preceding article, 17 Kim, Meyer, and Fleniken ͑KMF͒ have used this technique to carry out the IR ͑infrared͒ REMPI double resonance spectroscopy of the NO-Ne complex and hence extract information on the lowest bend-stretch levels of this complex, in a manner similar to that described earlier for NO-Ar. 18 Because of the simplicity of the NO-Ne system, and encouraged by the success of our calculations 18 of the bound states of the NO-Ar complex, we undertook a theoretical investigation of the lower bound states of the NO-Ne complex. We report in the next section the calculation of highquality ab initio potential energy surfaces, which are subse-quently used to calculate the bound states of the complex based on a full close-coupled expansion of the bound-state wavefunction.…”