Spectroscopic constants and the potential energy curve of the iodine weakly bound 0⁺_gstate correlating with the I(²P_1/2) + I(²P_1/2) dissociation limit

Abstract

The stepwise three-step three-colour I2(D0+u, vD, JD 0+g, v0, J0 B0+u, vB, JB X0+g, vX, JX) laser excitation scheme and rotational as well as rovibrational energy transfer processes in the 0+g state induced by collisions with He and Ar atoms are used for determination of rovibronic level energies of the weakly bound 0+g state correlating with the I(2P1/2) + I(2P1/2) dissociation limit. Dunham coefficients of the state, Yi0 (i = 0–3), Yi1 (i = 0–3) and Y02 for the = 0–16 and ≈ 14–135 ranges as well as the dissociation energy of the state, De, and equilibrium I–I distance of the state, Re, are determined. The potential energy curve of the state constructed using these constants is also reported.

Mid-Infrared Amplified Spontaneous Emission from the f′ 0g+ (1D2) Ion-Pair State and Spectroscopic Characterization of the Shallow 0g+ (ab) Valence State of I2

“…The vibrational distribution in the F ′ 0 u + ( 1 D 2 ) state was estimated by comparing calculated Franck–Condon factors with the experimental intensity distribution for the F ′ 0 u + ( 1 D 2 ) → 0 g + ( bb ) fluorescence band. The Franck–Condon factors were calculated using Le Roy’s RKR1 2.0, LEVEL 8.0, and BCONT 2.2 programs, and molecular constants reported in the literature. , In Figure a, the observed intensity contour (upper trace with black solid line) is very well reproduced by the simulated spectrum (lower trace), for which the relative populations of 0.10, 0.30, 1.00, 0.85, 0.10, and 0.01 were assumed for v F ′ = 7, 8, 9, 10, 11, and 12, respectively. Similarly, the fluorescence after the v f ′ = 2 excitation (Figure b) is also well reproduced by the simulation employing relative populations of 0.70, 1.00, 0.10, 0.05, 0.10, 0.50, and 0.05 for v F ′ = 4, 5, 6, 10, 15, 16, and 17, respectively.…”

Cross-sections of bound-free ${\rm I}_2 ( 0_g^ + , \mathop 1\nolimits_g (aa, ab)\buildrel{{\scriptstyle hv_{f}}}\over{\longleftarrow \!\!\!\! - \!\!\! - \!\!\! -}\mathop {B{\rm 0}}\nolimits_u^ + ,\;v_B = 18 - 21 )$ and bound–bound ${\rm I}_2 ( {\mathop 0\nolimits_g^ + , \mathop 1\nolimits_u (bb) \buildrel{{\scriptstyle hv_{f}}}\over{\longleftarrow \!\!\!\! - \!\!\! - \!\!\! -}\mathop {B{\rm 0}}\nolimits_u^ + , v_B = 21,\;J_B } )$ transitions at a fundamental harmonic of the Nd:YAG laser

“…There were three lines, ν 1 f = 9395.12 ± 0.02 cm −1 , ν 2 f = 9393.53 ± 0.07 cm −1 and ν 3 f = 9396.67±0.10 cm −1 , of generation of the YG981C laser employed with relative intensities 1-0.3-0.05. Their FWHMs were ≈0.14 cm −1 [20].…”

“…A detailed description of the experimental apparatus for excitation measurements of the I 2 (B, v B , J B → X) luminescence and the measurement procedures has been given elsewhere (see [20] and references therein). We used the Quantel system consisting of Nd:YAG YG981C (hν i f ) and tunable dye TDL90 (hν 1 ) lasers.…”

“…We successfully utilize three-step two-and three-color schemes of the population of ungerade D0 + u and gerade β1 g and D 2 g iodine state selected rovibronic levels, D, v D , J D , β, v β , J β and D , v D , J D via rovibronic states of intermediate B and 0 + g , 1u(bb) states (both latter correlate with the third dissociation limit, I( 2 P 1/2 + 2 P 1/2 ) (bb)) or their van der Waals complexes [16][17][18][19][20][21]. The 0 + g (bb) ← B0 + u transition is an EDA one, whereas the mechanism of the 1 u (bb) ← B0 + u electric dipole forbidden transition in pure iodine vapor is unknown at the moment (see [22] and references therein).…”

Molecular parameters for weakly bound 2g(aa,ab) and ${0}_{u}^{-}(ab)$ states of molecular iodine and dipole moment functions of transitions to these states

“…All measurements were carried out using an experimental setup described elsewhere (see [10,15] and references within). Briefly, we utilized a Quantel system which contains a YG981C Nd:YAG laser and two tunable TDL90 dye lasers.…”