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• 作者：Tibor Furtenbacher ; Attila G. Csá ; szá ; r
• 关键词：MARVEL ; Rotational spectra of water isotopologues ; Rotational energy levels ; Measurement standards
• 刊名：Journal of Quantitative Spectroscopy and Radiative Transfer
• 出版年：2008
• 期刊代码：70_00224073
• 类别：ch
• 出版时间：May 2008
• 卷：109
• 期：7
• 页码：1234-1251
• 文件大小：230 K

摘要

The protocol MARVEL, standing for measured active rotational–vibrational energy levels, is used to study high-accuracy measurements of rotational lines of four isotopologues of water, H₂¹⁶O, c35e2643ef7280d27909746dc" title="Click to view the MathML source" alt="Click to view the MathML source">H₂¹⁷O, H₂¹⁸O, and D₂¹⁶O, obtained by spectroscopy in the far-infrared (FIR) region of 15–170 cm⁻¹ by Matsushima et al. [Matsushima F, Odashima H, Iwasaki T, Tsunekawa S, Takagi K. Frequency measurement of pure rotational transitions of H₂O from 0.5 to 5 THz. J Mol Struct 1995; 352/353, 371–8; Matsushima F, Nagase H, Nakauchi T, Odashima H, Takagi K. Frequency measurement of pure rotational transitions of H₂¹⁷O and H₂¹⁸O from 0.5 to 5 THz. J Mol Spectrosc 1999;193: 217–23; Matsushima F, Matsunaga M, Qian GY, Ohtaki Y, Wang RL, Takagi K. Frequency measurement of pure rotational transitions of D₂O from 0.5 to 5 THz. J Mol Spectrosc 2001;206: 41–6; Matsushima F, Tomatsu N, Nagai T, Moriwaki Y, Takagi K. Frequency measurement of pure rotational transitions in the v₂=1 state of H₂O. J Mol Spectrosc 2006;235: 190–5]. MARVEL validates the high accuracy of most of the measured line positions. It results in a considerable number of energy levels with an average internal uncertainty of only 40 kHz (2σ). It also supports serious inaccuracy problems when Watson-type A-reduced Hamiltonians are used for predicting the highly accurate rotational measurements for water. Finally, MARVEL suggests a large number of para-water levels, for example 41 for 53c809825000e28" title="Click to view the MathML source" alt="Click to view the MathML source">H₂¹⁶O, which are candidates for becoming frequency standards in the FIR region of 15–170 cm⁻¹ (the 0.5–5 THz window) when an accuracy of about 0.1 MHz is deemed to be sufficient.