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Gas phase electronic spectra of the linear carbon chains HC[sub 2n+1]H (n=3–6,9).
- Source :
-
Journal of Chemical Physics . 7/8/2003, Vol. 119 Issue 2, p814. 6p. 2 Charts, 4 Graphs. - Publication Year :
- 2003
-
Abstract
- The B [SUP3]Σ[SUP-,SUBg] ← X[SUP3]Σ[SUP-,SUBg] transitions of HC[SUB13]H and HC[SUB19]H have been measured in the gas phase, exhibiting broad, Lorentzian shaped bands. More extensive A [SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg] spectra have been observed for HC[SUB2n+1]H (n = 3 - 6) than before with many new vibronic bands identified. The spectra were obtained by means of a mass selective resonant two-color two-photon ionization technique coupled to a supersonic plasma source. The electronic structures of this series of molecules (n = 2 - 9) in both the ground and excited states have been investigated using DFT, MP2, and state-averaged CASSCF theories. The three lowest dipole allowed electronic transition systems are A [SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg], B[SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg], and C [SUP3]Γ[SUBu] ← X[SUP3]Σ[SUP-,SUBg], located, for the smaller members of the series, in the visible, UV and VUV range, respectively. The A [SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg] system is found to be of medium intensity and the B[SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg] transition is predicted to be very strong. This is a result of configuration mixing in the excited states. The oscillator strength of the lowest energy transition is not strongly dependent on the length of the chain, but that of the B[SUP3]Σ[SUP-,SUBu] ← X[SUP3]Σ[SUP-,SUBg] system increases monotonically with size. The C [SUP3]Γ[SUBu] state is Rydberg in character. The astrophysical implications are considered and an upper limit of the column densities of these carbon chains in diffuse clouds has been estimated as 10[SUP13] cm[SUP-2], based on calculated oscillator strengths. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219606
- Volume :
- 119
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- Journal of Chemical Physics
- Publication Type :
- Academic Journal
- Accession number :
- 10113251
- Full Text :
- https://doi.org/10.1063/1.1578476