| 释义 |
predissociˈation Physics and Chem.
[pre- A. 2.]
The passage of a molecule between a quantized vibrational and rotational state (above its ground state) and a dissociated state of the same energy that is not quantized, the occurrence of which results in certain bands in the spectrum of the molecule being diffuse instead of having the normal rotational fine structure. Freq. attrib.
1924Henri & Teves in Nature 20 Dec. 895/1 The molecule can be modified in its internal structure: the atoms are driven apart, the bonds are weakened, the molecule becomes more reactive, and the rotational movements are no longer quantified. This first modification is a preliminary preparation of the molecule for its total dissociation, and it is necessary to introduce a new term for this change. We propose to denote it by the term predissociation of the molecule. 1930Physical Rev. XXXV. 1028 (heading) Predissociation of diatomic molecules from high rotational states. 1944Glasstone Theoret. Chem. iv. 188 In some cases the predissociation spectrum is followed by a region of continuous absorption but, in other instances, bands with fine structure are found on both long and short wave sides of the predissociation bands. 1962P. J. & B. Durrant Introd. Adv. Inorg. Chem. vii. 222 Predissociation is commonly shown only in absorption, not in emission. 1966Barnard & Mansell Fund. Physical Chem. ii. 96 A molecule undergoing pre-dissociation will dissociate within the time of one rotation and the rotational fine structure will tend to be lost in the gas phase spectrum. 1977Sci. Amer. Feb. 95/1 Instead the molecule is disassembled at a lower energy through a phenomenon called predissociation. |