General principles of wave-mechanical treatment

This is clearly a wave motion moving from left to right (Fig. 6). It is complex, and the number of particles per unit volume usually written simply 2, is 

For the problem of vibrational relaxation, the frequency of the beam is not affected when the speed is changed by application of a field (i.e. intermolecular force), and for brevity the time factor is omitted. The wavelength is 2n/k, and because of the de Broglie relationship mvX = h 

The above wave functions are solutions of the wave equation 

If the beam enters a retarding field due to a potential V(x), the wavelength at all points is given by the well known equation 

One of the simplest of scattering problems, which can easily be solved by describing a beam as 

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