No abstract

The ν1 band of the DO2 radical was observed by difference frequency laser and diode laser spectroscopy with Zeeman modulation. The radical was produced by a 60 Hz discharge in a mixture of CH3OD or CD3OD and O2 flowing through a multiple reflection absorption cell. The observed lines, 181 in total, of six subbands with Ka =2←3, 1←2, 0←1, 1←0, 2←1, and 3←2 were included in a least-squares analysis to determine molecular parameters for the upper state: A=326 929.3(92), B=31 683.68(36), C=28 779.96(46), εaa=−26 039(38), εbb=−381.7(29), εcc =4.3(22), in MHz, and the band origin ν0=2 549.224 65(36) cm−1, where the values in parentheses denote one standard error in units of the last quoted decimal place. By combining this data with that for the ν2 and ν3 bands of DO2 by Uehara et al. and that for HO2 already available in the literature, the equilibrium structure of the hydroperoxyl radical was calculated with estimated uncertainties: re (O–H)=0.9707±0.0020 Å, re(O–O)=1.330 54 ±0.000 85 Å, and θe (HOO)=104.29±0.31 Å.

= -J V2b(3:)~a(3:)~b(3:)dT. (A7) The relations in Eq. (A7) are derived as follows: Since V 2a is not totally symmetric, J V 2a (3:) [~a2(3:) +~b2(3:) JdT=O. (A8) It then follows that J V2a(3:)~a2(3:)dT= -I V2a(3:)#(3:)dT=a. On the other hand, if an operator Cs is applied to a, Csl V2aC3:)~a2(3:)dT= -~J [V2a (3:) +v'5V 2b(3:) J X[~a(3:) +v'5~b(3:) J 2 dT = -~J V2a(3:)~2(3:)dT -~J V2b(3:)~a(3:)~(3:)dT =a, and hence (A9) By substituting Eqs. (A3) and (A6) into Eq. (Al), it is easily shown that the coordinates Qaa,Sb, or Sc and Q4a,4b. or 4. undergo the usual equations for the threedimensional harmonic oscillator, whereas the totally symmetric coordinate Ql satisfies the equation [ -!1i 2 (d2/dQ12) +fQl+!~qQ12~(Ql) =E~(Ql), (AlO) and Q20 and Q2b satisfies Eqs. (6) in the text.The molecular structures of VCl4 and TiCl4 have been determined by gas electron diffraction. The mean square amplitude of the CI-CI distance in VCl4 is found to be abnormally large compared with that of TiCI4. This is attributed to the vibronic interactions in VCI4. The observed mean square amplitude has led to the evaluation of the first-order vibronic interaction constant 1 a' I. Other experimental results, such as bond lengths, the shrinkage effect, and vibrational spectra are discussed in relation to the theory of vibronic interactions.

Rotational transitions of HF that are important as a wavenumber standard have been analyzed by simultaneous fitting of the reported rotational and vibrational-rotational transitions plus rotational measurements of the present study with the non-Born-Oppenheimer effective Hamiltonian expressed with the optimal parameters, i.e., the determinable clusters of the expansion coefficients of the correction functions for the breakdown of the Born-Oppenheimer approximation. Since the spectral fit is made with the analytical solution of the Schrödinger equation, one can easily reproduce the fitting procedure. This is the first example of the non-Born-Oppenheimer analysis of a single isotopologue with physically meaningful parameters based on the traditional concept of the molecular constants. Fitting of a data set for HF has generated 15 independent parameter values that include 4 determinable clusters of the expansion coefficients. These 15 parameters are sufficient to generate 41 Yij coefficients and 72 rotational constants, which provide comprehensive sets of molecular constants of HF.

Analytic expressions for Born–Oppenheimer corrections to Dunham’s Yij with optimal fitting parameters, i.e., determinable clusters of expansion coefficients, are applied in analysis of data of reported vibrational–rotational and rotational transitions of HCl. In this method of analysis the choices of a set of fitting parameters and also a corresponding set of Yij that connects the fitting parameters with the term values are unique. A layered structure for empirical parameters Δij is revealed. All spectral lines of four isotopomers of HCl are simultaneously fitted to a single set of molecular constants well within the experimental errors. The approach thus provides a better fit of smaller standard deviations with fewer number of adjustable parameters than from other methods of analysis. The determined values for the coefficients of adiabatic effects s1H and s1Cl reveal the wobble-stretch term to be unimportant in the adiabatic correction for HCl.