High resolution FTIR spectra of AsD3 in the 20-1000 cm−1 region. The ground, 98, v2 = 1 and v4 = 1 states

• Published in: Molecular physics Vol. 98; no. 9; pp. 589 - 604
• Main Authors: BÜRGER, H., JERZEMBECK, W., RULAND, H., WIRTZ, M.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 10-05-2000
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268970009483326

The pure rotational spectrum of the near-spherical oblate symmetric top AsD
3
has been recorded in the 20-120cm
−
′ region with a resolution of 2.3 × 10
−3
m
−1
employing an FT interferometer. Rotational transitions with 5 ⩽ J ⩽ 29 and 0 ⩽ X ⩽ 25 of the ground state (GS) and the v
2
= 1 and v
4
= 1 excited states have been assigned. Splittings were observed for the GS, 98, K = 3 and 6 levels, the K = 3 levels of v
2
and the kl = −2, 1, 4 and 7 levels of v
4
. Furthermore the x,y Coriolis coupled v
2
and v
4
bands, v
0
2
= 654.4149cm
−1
, and v
0
4
= 714.3399 cm
−1
, have been examined with a resolution of 2.4 × 10
−3
cm
−1
, and ca. 2500 allowed and 336 'forbidden' lines with J′
max
= 31 and K′
max
= 28 have been assigned. Appropriately weighted GS data comprising FIR lines, allowed and 'forbidden' (up to ΔK = ±6) GS combination differences, mmw data, and ΔJ = 0, ΔK = ±1 distortion moment transitions were fitted together, and GS parameters complete through H parameters have been determined. Two different reductions of the Hamiltonian, either with ΔK = ±6 (h
3
) or ΔK = ±3 (ε) off-diagonal elements, have been employed. Equivalence of these reductions up to J = 22 was established while for J > 22 the ε reduction is superior. The v
2
and v
4
data have been fitted with two equivalent models based on different reductions of the rovibrational Hamiltonian. In addition to the dominating x,y Coriolis resonance, ζ
y
24
0.520, Δ(k − l) = ±3 and ±6 interactions are important and were accounted for by the models. The transition moment ratio |M
4
: M
2
| =0.75 has been determined, with a positive sign of the product M
2
ζ
y
24
M
4
. An improved r
0
structure, r
0
(AsD) = 1.51753 Å and α
0
(DAsD) = 92.000°, has been determined.