问题：就是一点知识
类型：推荐
提问：seamanhai
等级：▲▲▲
版块：电化学(fafa_du,James,seamanhai,)
信誉：30%
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阅读：629
时间：2005-09-28 17:44:11 编辑加入/取消收藏订制/取消短消息举报该贴

of molecules or molecular fragments. Data displayed for ionization energies, electron affinities and acidities are experimental values as reported in the literature, and are given along with a citation of the original paper; values for proton affinities and gas phase basicities are taken from a new re-evaluation of the relevant thermochemical scales, and original references are not given in the current version of the WebBook. For the experimental data, guidance is provided (at least for the more common molecules) in the selection of a "best" value, when several different values have been reported for a quantity. Values for the gas phase enthalpies of formation of some of the common positive and negative ions derived from these data are displayed. The values for enthalpies of formation are presented using the so-called Ion Convention for treating the thermochemistry of the electron (rather than the Electron Convention commonly used in thermodynamics compilations).

In the August 1997 release of the WebBook, for the first time, the NIST Positive Ion (ionization energies, appearance energies), Proton Affinity (gas phase basicities, proton affinities) and Negative Ion (electron affinities, gas phase acidities) databases are combined into a single searchable Ion Energetics database. Because the Positive and Negative Ion databases were developed and maintained separately, the structures of the two sets of files are different, resulting in some inconsistencies in the way analogous data are presented in the WebBook. In future updates, these inconsistencies will be removed, but at the present time users should be aware that (a) data relevant to formation of positive ions are accessed through a search for the precursor neutral species while data on the thermochemistry of the anion is found by searching for the anion; (b) when the box on the entry screen denoting a search for "Ion Energetics" data is checked, available data on gas phase basicities and proton affinities will be displayed with every "hit", while available data on gas phase acidities will not appear; in order to access gas phase acidity data, the user must also click on the box in the entry screen labeled "Reaction". For the same reason, the user will find that sometimes the same experimental technique is designated by two different acronyms in accessing results on positive and negative ions; because these acronyms are fully defined, it is hoped that this will not cause confusion.

The current collection is an update and extension of several earlier data compilations / evaluations, including all the data which appeared in previous publications [1, 2, 3, 4, 7] and electronic databases [5, 9], and the new re-evaluation of the proton affinity scale [10], as well as data which has appeared in the literature since the release of the most recent electronic database [9].

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