Suitable Stress Waveforms for the Deformation-Induced Electronic Excitation in Crystals

A quantum mechanical approach is made to the deformation-induced electronic excitation in crystals. The ML intensity is assumed to be related to the transition probability P(m, n) from n^th to m^th state, and it may be expressed as I_ML = βP(m, n) where P(m, n) = 4π²/hα² |σ_mn (ω_mn)|² ·( n · μ )_mn·². It is shown that the ML excitation can take place only by the time-dependent applied stress. The ML excitation probability is analysed for different waveforms of the applied stress such as constant stress, δ-function, rectangular stress, single sided and double sided exponential stress, unit step function, external sinusoidal signals cos ω₀t and sin ω₀t, external exponential function, a periodic function and the stress of sequence of equidistant impulses of unit strength separated by a particular time. It is found that when the stress is a δ-function, a rectangular waveform, sinusoidal singals cos ω₀t and sin ω₀t or a sequence of equidistant impulses of unit strength and separated by a particular time, then there is a considerable probability of electronic excitation by the resonance transfer mechanism between the Fourier transform of the stress waveform and the frequency of the emitting electronic system i.e. (E₂ – E₁)/h.