Principles of Molecular Spectroscopy Quantized Energy States

Frequency is inversely proportional to wavelength the greater the frequency, the shorter the wavelength. 

Energy is directly proportional to frequency electromagnetic radiation of higher frequency possesses more energy than radiation of lower frequency. 

2 PRINCIPLES OF MOLECULAR SPECTROSCOPY QUANTIZED ENERGY STATES 

Spectrometers are designed to measure the absorption of electromagnetic radiation by a sample. Basically, a spectrometer consists of a source of radiation, a compartment containing the sample through which the radiation passes, and a detector. The frequency of radiation is continuously varied, and its intensity at the detector is compared with that at the source. When the frequency is reached at which the sample absorbs radiation, the detector senses a decrease in intensity. The relation between frequency and absorption is plotted on a strip chart and is called a spectrum. A spectrum consists of a series of peaks at particular frequencies its interpretation can provide structural information. Each type of spectroscopy developed independently of the others, and so the format followed in presenting the data is different for each one. An NMR spectrum looks different from an IR spectrum, and both look different from a UV-VIS spectrum. 

FIGURE 13.2 Two energy states of a molecule. Absorption of energy equal to 2 1 excites a molecule from its lower energy state to the next higher state. 

When examining Fignre 13.1 be sure to keep the following two relationships in mind  

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Principles of Molecular Spectroscopy Quantized Energy States... 

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