Rotational structure and dissociation of the Rydberg states of CO investigated by ion-dip spectroscopy

Abstract

In a series of spectroscopic work of the Rydberg states of CO, we present the rotational analysis of the v=0 and 1 levels of the singlet ns, np, nd and nf-Rydberg states (n=4–7). The spectra were measured by ion-dip spectroscopy with triple resonance excitation via the 3sσ:B 1Σ+ or the 3pσ:C 1Σ+ state. All the spectra were rotationally well resolved and the term value, quantum defect and the rotational constant were obtained for each state. Through the analysis of the rotational structure, the coupling between the Rydberg electron and the ion core has been investigated. For the np-Rydberg states, a switching from Hund’s case (b) to (d) was clearly observed with the increase of n. A significant perturbation was observed in the 6pπ 1Π and 7pπ 1Π states and it is suggested that these states are perturbed by the state with the same symmetry. For the nf-Rydberg states, the observed electronic energy was well analyzed by the long range force model and the precise ionization potential was obtained. The Rydberg↔valence and inter-Rydberg states interactions were also investigated. For the ns-Rydberg states, the interaction matrix element with the repulsive state was estimated from the measurement of linewidth of the rotational levels. The potential curve of the repulsive state to which ns-Rydberg states predissociate was also determined. Selective predissociation was found for the e-symmetry levels both in the v=0 and 1 levels of the nf-Rydberg state. A strong interaction between the v=0 levels of the 6d- and 7s-Rydberg states was observed.

Carbon Monoxide Triplet Rydberg Series in the f Complex Region

“…The strongest P-and R-form lines reach about half of their intensity. While the assumption of equal radial electronic integrals may be a rather strong simplification, this pattern of line intensities is in qualitative agreement with the singlet Rydberg spectra recorded by Komatsu et al (9).…”

“…A large number of states in the energy range from 95 000 to 110 000 cm −1 was detected using absorption spectroscopy (2,3), extreme ultraviolet (XUV) laser spectroscopy (4) and multiphoton excitation (5). The power of state-selective laser techniques was shown in a series of articles by Ebata and co-workers (6)(7)(8)(9) who performed a comprehensive study of the s, p, d, and f singlet Rydberg series (v = 0 and 1) up to a principal quantum number of n = 10. Still, many perturbations, especially those caused by high-lying valence states, are not yet fully understood (10).…”

Branching Ratio Measurements for Vacuum Ultraviolet Photodissociation of 12C16O

“…The branching ratio of the spin-forbidden channel is zero as shown in Table 1, thus it does not dissociate into the triplet channel C( 1 D) + O( 3 P). Komatsu et al 32 tried to understand the predissociation dynamics for this state into the ground channel; they tentatively concluded that it is more likely this state is interacting with a repulsive 1 Π state other than the wellknown D′ 1 Σ + state. With the information in the present study, we cannot determine the repulsive state that is responsible for the dissociation of the J(4sσ) 1 Σ + (v′ = 1) state into the channel of C( 3 P) + O( 3 P).…”

High-resolution study of oscillator strengths and predissociation rates for12C16O

“…After comparison with the measured spectrum, a small discrepancy between the R-and P-branch intensities was Notes. Comparison with previous predissociation rate results: E91 (Eidelsberg et al 1991), L92b (Levelt et al 1992b), D93 (Drabbels et al 1993), E94 ), E06 (Eidelsberg et al 2006), L92a (Levelt et al 1992), K95 (Komatsu et al 1995). (a) Predissociation rates in units of (10 11 s −1 ); (b) x = J(J+1); (c) held fixed; (d) perturbation results in anomalous line broadening pattern; rate is ∼6 for J < 6, 1.8(6) for J = 6, and 3.3 + 0.017 x for J > 6 (see text).…”

“…Eidelsberg et al (2006) also reported W -X f -values for the 13 C 16 O and 13 C 18 O isotopologues. A series of laser-based measurements of line widths (Levelt et al 1992a,b;Eikema et al 1994;Komatsu et al 1995) were used to determine predissociation rates for the W(0) and W(2) levels, and Eidelsberg et al (1991Eidelsberg et al ( , 2006 reported line width and predissociation rates for all four W vibrational levels from their photoabsorption spectra.…”