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1: Review and motivation

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    75273
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    The emission spectra of atoms provide a fingerprint of each element.

    spectra.gif

    Many elements were discovered by examining line spectra (e.g., helium, thallium). The complexity of line spectra increases as the number of electrons in the atom increases. It seems reasonable to conclude that understanding the origin of the various lines in atomic emission spectra will lead to an understanding of the structure of atoms.

    Furthermore, we know that various substances absorb particular wavelengths of light in characteristic ways (e.g., the various colors of dye molecules and transition metal complexes, and the various infrared signatures we learned in organic chemistry). It turns out that the answers to all of these phenomena are contained in subdiscipline of quantum chemistry, which is the application of the paradigms of quantum mechanics to the field of chemistry. Quantum chemistry provides the tools by which we can gain a fundamental understanding (as opposed to the largely phenomenological methods used in your previous studies) of chemical bonding, reactivity, and spectroscopy.

    Spectroscopy, the study of how light and matter interact, holds a special place in the story of quantum chemistry. It is both one of the original sources of the inspiration of the field and one of the fundamental tools used to study quantum chemistry.


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