Qualitative Analysis

The identification of an unknown is commonly carried out by comparison with a library of reference gas-phase spectra. The absorption process of an atom or a molecule in the gas phase is free from any influence, which reproduces not only the unique character of the electronic transitions, but also of the accompanying simultaneous changes in the vibra-tional states. This gives rise to spectral shapes which are strictly defined and, in most cases, accompanied by fine structures. Therefore the UV spectra are well suited for identification by means of a computer-based spectral search against a reference spectrum library. A spectrum library of & 1000 gas-phase UV spectra recorded in the wavelength region of 168-330 nm has been established. A commercially available IR search program has been used with success for identification. Because of the relatively small size of this library, the identification possibilities are limited. Nevertheless, identification of classes of compounds can most often be directly pointed out. The compounds containing the same functional group show a number of characteristic similarities, but at the same time clear differences between individuals within a group are observed. The exceptions are cases when various straight alkyl chains are involved. The spectra of acetophenone and propiophenone, for example, are hard to distinguish from each other.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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