A Reanalysis of theA1Π–X1Σ+Transition of AlBr

✍ Scribed by Patrick E. Fleming; C.Weldon Mathews

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 184 KB
• Volume: 175
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1996.0005

✦ Synopsis

The A 1 P-X 1 S / transition of aluminum monobromide (AlBr) near 2800 A ˚was recorded using a Bruker IFS 120 HR Fourier transform spectrometer at nominal resolutions of 4 and 0.03 cm 01 . All bands show P, Q, and R branches and all are degraded to longer wavelengths. The 0-0 band is the most intense and the D£ Å 0 sequence dominates the observed spectrum. Each band appears doubled due to the natural isotopic abundances of 79 Br (50.69%) and 81 Br (49.31%). Band origin shifts due to isotopic substitution of bromine were examined to confirm the assignments of isotopic species. The rotational structure of the 0-1, 1-2, 0-0, 1-1, and 2-2 bands was assigned and fitted. These data were merged with previously reported photographic data for the 1-0, 2-1, 3-2, 2-0, and 3-1 bands and also infrared and microwave measurements to provide an improved set of constants for both electronic states. The rotational constants for each vibrational level in the X 1 S / state vary smoothly with increasing vibrational quantum number and thus an expansion of the constants in terms of equilibrium values is recommended. An expansion of the A 1 P rotational constants in terms of equilibrium values is not recommended as the distortion constants do not change smoothly with increasing vibrational quantum number. Therefore, the rotational constants for the A 1 P state were determined for each individual vibrational level. This approach leads to vastly improved vibrational constants for the A 1 P state by reducing correlations between rotational and vibrational constants. This problem is serious for the A 1 P state owing to severe departures from harmonic behavior in the £ Å 2 and £ Å 3 levels.