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凡得瓦分子
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凡得瓦分子(vdW分子)是键结力很弱的分子或原子群,其结合是靠著范德华力或氢键等分子间作用力[1]。此名词起源于1970年代,可以用分子束微波光谱(英语:microwave spectroscopy)观察到稳定的分子簇。
例子
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针对一些凡得瓦分子已有相关的研究,例如Ar2(英语:Diargon)、H2-Ar、H2O-Ar、benzene-Ar、(H2O)2和(HF)2。其他的包括最大的双原子分子氦二聚体和LiHe(英语:LiHe)[2][3]。
超声束光谱
在(超声束)分子束中的温度很低(约低于5 K)。凡得瓦分子在此低温下会稳定,可以用微波、远红外线光谱(英语:far-infrared spectroscopy)及其他光谱侦测到[4]。 在冷平衡气体中也会形成凡得瓦分子,不过其浓度很小,而且和温度有关。目前已观察到气体中凡得瓦分子的旋转跃迁和振动跃迁,主要是用紫外以及红外光谱来观察。
凡得瓦分子多半是非常的不具刚性,而且可以用很低的能量壁垒分隔出不同的流变分子,因此在远红外光谱中看到的穿隧分裂(tunneling splittings)相对较大[5]。在远红外线光谱中可以观察到凡得瓦分子的分子间振动、旋转以及穿隧运动(VRT)。 凡得瓦分子的VRT光谱研究是目前了解分子间作用力最直接的途径[6]。
相关条目
- 范德华半径
- 凡得瓦应变(英语:Van der Waals strain)
- 凡得瓦表面(英语:Van der Waals surface)
- 此领域的研究者:
- Donald Levy(英语:Donald Levy)
- Richard J. Saykally(英语:Richard J. Saykally)
- 理查德·斯莫利
- William Klemperer(英语:William Klemperer)
参考资料
- Blaney, B L; Ewing, G E. Van Der Waals Molecules. Annual Review of Physical Chemistry. 1976, 27 (1): 553–584. Bibcode:1976ARPC...27..553B. ISSN 0066-426X. doi:10.1146/annurev.pc.27.100176.003005.
- Friedrich, Bretislav. A Fragile Union Between Li and He Atoms. Physics. 8 April 2013, 6: 42 [2021-08-15]. Bibcode:2013PhyOJ...6...42F. doi:10.1103/Physics.6.42
. (原始内容存档于2017-08-29).
- Joshua Jortner. Van der Waals Molecules (Donald Levy). Advances in Chemical Physics, Photoselective Chemistry. John Wiley & Sons. 8 September 2009: 323– [2021-08-15]. ISBN 978-0-470-14313-1. (原始内容存档于2021-08-28).
- Smalley, Richard E.; Wharton, Lennard; Levy, Donald H. Molecular optical spectroscopy with supersonic beams and jets. Accounts of Chemical Research. 1977, 10 (4): 139–145 [2021-08-15]. Bibcode:1977mosw.book.....S. ISSN 0001-4842. doi:10.1021/ar50112a006. (原始内容存档于2017-09-23).
- Hutson, J M. Intermolecular Forces from the Spectroscopy of Van Der Waals Molecules. Annual Review of Physical Chemistry. 1990, 41 (1): 123–154. Bibcode:1990ARPC...41..123H. ISSN 0066-426X. doi:10.1146/annurev.pc.41.100190.001011.
- Miller, R. E. Infrared laser photodissociation and spectroscopy of van der Waals molecules. The Journal of Physical Chemistry. 1986, 90 (15): 3301–3313. ISSN 0022-3654. doi:10.1021/j100406a003.
延伸阅读
- So far three special issues of Chemical Reviews have been devoted to vdW molecules: I. Vol. 88(6) (1988). II. Vol. 94(7) (1994). III. Vol. 100(11) (2000).
- Early reviews of vdW molecules: G. E. Ewing, Accounts of Chemical Research, Vol. 8, pp. 185-192, (1975): Structure and Properties of Van der Waals molecules. B. L. Blaney and G. E. Ewing, Annual Review of Physical Chemistry, Vol. 27, pp. 553-586 (1976): Van der Waals Molecules.
- About VRT spectroscopy: G. A. Blake, et al., Review Scientific Instruments, Vol. 62, p. 1693, 1701 (1991). H. Linnartz, W.L. Meerts, and M. Havenith, Chemical Physics, Vol. 193, p. 327 (1995).