Patricia C. Tellinghuisen

Spectroscopic studies of diatomic noble gas halides. IV. Vibrational and rotational constants for the X, B, and D states of XeF

The B→X and D→X systems of XeF are recorded by photographing the emission from the low‐pressure Xe*/XeF2 and Ar*/XeF2 reactions. A rotational analysis is obtained for the 1–2 band of B–X, for which isotopic blending is negligible. Vibrational parameters for the X, B, and D states are derived from a direct, weighted least‐squares fit of all assignments for both transitions. Rotational parameters are deduced from the vibrational dependence of the band shapes and intensities. Some significant results of this analysis are ReX=2.293 a, ReB=2.631 a, ReD=2.51 A, ωeX=225 cm−1, ωeB=309.0 cm−1, ωeD=350.1 cm−1, and DeX=1175 cm−1. The Franck–Condon factors for many of the bands in both systems show a strong rotational dependence, which is to be expected in transitions of this type, for reasons discussed herein.

Spectroscopic studies of diatomic noble gas halides. III. Analysis of XeF 3500 Å band system

B→X spontaneous and stimulated emission spectra of XeF have been photographed at medium resolution (2.0 A/mm) and vibrationally analyzed. The assignments are made with the aid of trial‐and‐error Franck–Condon calculations and band profile simulations, which are described in detail. The strong laser emission near 3511 A is primarily due to densely overlapped rotational lines in the 1–4 vibronic band, and that near 3532 A probably includes numerous rotational transitions in the 0–2, 0–3, and 1–6 bands.

B → X transitions in HgCl and HgI

The B → X spectra of HgCl and HgI are studied at high resolution for the single isotopic species, 200Hg35Cl, 200Hg127I, and 200Hg129I. For HgI the analysis indicates that the v″ numbering should be decreased by one unit from the previous assignment. For both molecules the analyses deviate progressively from the previous assignments at high v″, extrapolating to lower estimates of the ground‐state dissociation energies. Franck–Condon calculations yield ΔRe (=Re′ −Re″) =0.60A for HgCl and 0.49 A for HgI. The strongest laser features previously reported for HgCl occur near the heads of the overlapped 0–22, 1–23, 2–24, and 3–25 bands. The HgI laser operates in the region of the 0–14, 0–15, 1–15, 1–16, 2–17, and 2–18 bands.

The emission spectrum of 200Hg127I

Abstract The ultraviolet emission systems of HgI— C → X , D → X , F 3 → X , G → X , and H → X —are photographed and analyzed using tesla-discharge sources containing isotopically pure 200 Hg. The previous assignment for F 3 → X is revised, the main change being a decrease by 3 units in the v ″ numbering. Results for the other systems corroborate the existing interpretations, except that for C → X there are prominent intensity gaps in the unresolved rotational structure of the bands, not reported previously for “natural” HgI spectra. These gaps are attributed to perturbations of the C state by high levels ( v ≈ 90) of the B state. The data for these systems are combined with existing B → X data for 200 Hg 127 I and 200 Hg 129 I and fitted simultaneously to yield optimal vibrational parameters for all states. In this analysis the X state is fitted to a mixed representation—a polynomial in ( v + 1 2 ) for v ≤ 20 and a near-dissociation expansion for v ≥ 20, with G v and its first derivative constrained to be continuous at v = 20. The revised estimate of D e for X is 2800 ± 40 cm −1 . The recommended vibrational parameters (cm −1 ) for v ≤ 20 are ω e = 125.41, ω e x e = 1.009, ω e y e = −0.0159.

The emission of BrCl: analysis of the D'→A' and E→B transitions

Abstract The emission spectrum of BrCl in Ar is studied using Tesla discharge sources containing single isotopomers of BrCl. The D′(2 3P2) → A′ (3Π2) and E(0+3P2) → B(3Π0+) transitions are identified and analyzed, yielding the following values (cm−1) for the fundamental constants of the new states: A′:Te≈14700, ωe=232, Re=2.55 A; D′: Te≈48400, ωe=197.9, Re=3.113 A; E: Te=48760, ωe=196, Re≈3.05 A.

B→X transition in 136Xe 19F

The B→X emission spectrum is analyzed for the single isotopomer 136Xe 19F. Thirteen v′‐v″ bands spanning v′=0–4 and v″=0–5 have been rotationally analyzed. The analysis yields greatly improved spectroscopic constants, permitting precise identification of most of the features in the XeF laser spectrum. No evidence is found for C→X emission in the normal sense. However, it is possible that several previously unassigned features, including one or more reported laser lines, constitute C→X emission enabled through intensity borrowing from B‐X by B‐C perturbative mixing.

The f → X transition in ICl

Abstract The f0 + ( 3 P 0 ) → X 1 Σ + band system of ICl (3000–3300 A) is photographed at high resolution from tesla discharge sources containing the individual isotopomers, I35Cl and I37Cl. The rotational analysis of 24 v′-v″ bands includes ∼ 1900 assigned lines spanning v′ = 0–2 and v″ = 39–50. The data yield and improved description of the probed regions of both states, which have been observed before but not in this emission transition. Recommended constants for the f state (valid for v = 0–14, units cm−1) are: Te = 44 924.375, ωe = 184.158, ωexe = 0.7439, ωeye = 0.00268, Be = 0.057925, αe = 2.32 × 10−4, γe = 5.4 × 10−7.

The G → A transition in ICl

Abstract The G[1( 3 P 1 )] → A 3 Π 1 band system of ICl (3250–3400 A) is photographed at high resolution from tesla discharge sources containing the individual isotopomers, I 35 Cl and I 37 Cl. The rotational analysis of 24 v ′- v ″ bands includes ∼1700 assigned lines spanning v ′ = 0–2 and v ″ = 8–15. Most of the data involve the previously unreported v ′ = 0 level of the G state, for which higher v levels have been studied before but not in this emission spectrum. The analysis generally corroborates the previous descriptions of both states.