Doppler-free optical–optical double resonance polarization spectroscopy of the K8539Rb 1 1Π and 2 1Π states

Abstract

High resolution spectra of the 1 1Π(v′=13–69,J′)←X 1Σ+(v″,J″) and 2 1Π(v′=0–13,J′)←X 1Σ+(v″,J″) transitions of the K8539Rb molecule have been measured with the technique of Doppler-free optical–optical double resonance polarization spectroscopy (OODRPS). Molecular constants of the 1 1Π(v=13–69) and 2 1Π(v=0–13) levels have been determined, and potential energy curves constructed by the RKR method. The RKR potential of the 1 1Π state was found to have a distortion at outer wall, which originates from an avoided crossing of two 1Π states. The perturbations between the 1 1Π(v1,J) and 2 1Π(v2,J) levels were found from the energy shifts of the rotational levels. The magnitude of the nonadiabatic interaction between the 1 1Π(v1=54) and 2 1Π(v2=9) levels, 〈1 1Π(v1=54)|TN|2 1Π(v2=9)〉, was evaluated to be 2.2 cm−1 by a least squares fitting to the energy shifts of the 1 1Π(v1=54,J=20–33) levels. The line intensities were observed to change dramatically around the maximum energy shift. These intensity anomalies are interpreted as an interference effect, which occurs when two interacting levels have comparable transition moments. A remarkable line broadening was observed for the transitions to the 1 1Π(v⩾63) levels, and it was identified as originating from the predissociation to K(4s2S1/2)+Rb(5p2P1/2) atoms. The dissociation energies of the X 1Σ+, 1 1Π, and 2 1Π states have been determined to be 4217.4±0.8, 2021.5±0.8, and 1050.0±0.8 cm−1, respectively.

Twofold diabatization of the KRb(1–2)Π1complex in the framework ofab initioand deperturbation approaches

“…3). The CC diabatic model also improves the representation of the vibronic E exp v ′ termvalues 13,14,17 up to the excitation energies ∼ 16400 cm −1 (see Fig. 8b).…”

“…1 Π(v ′ 1 ≥ 63) levels lying just above the fine 4 2 S 1/2 (K)+5 2 P 1/2 (Rb) asymptotic undergo a predissociation effect 14 . Thus, raw experimental termvalues corresponding to high v ′ , J ′ -levels of the (1 ∼ 2) 1 Π complex would be certainly useful for the comprehensive deperturbation analysis since the "effective" band constants indispensably "absorb" the spin0orbit perturbation effect in the high energy region.…”

“…In the present work, we performed a twofold diabatization of the KRb 1 1 Π ∼ 2 1 Π complex by means of mutually complementary methods, namely: ab initio electronic structure calculations and direct coupled-channel (CC) deperturbation treatment of experimental termvalues [12][13][14][15][16][17] .…”

“…The mutually perturbed 1 1 Π and 2 1 Π states converging to the second K(4 2 S)+Rb(5 2 P) and third K(4 2 P)+Rb(5 2 S) dissociation thresholds were investigated 13,14 using Doppler-free optical-optical double resonance polarization spectroscopy (OODRPS). In the sub- FIG.…”

Theoretical study of highly-excited states of KRb molecule

“…Polar alkali molecules, and in particular KRb, have recently been the object of intensive experimental [1][2][3][4][5][6][7][8][9][10][11][12] and theoretical [13][14][15][16] studies. For instance, the KRb molecule often serves as an example of a reactive species in order to explain the collision rates of trapped and ultracold polar molecules (e.g.…”