Some 'relativistic' effects involving radiation from nonrelativistic particles in a medium

Bremsstrahlung and synchrotron radiation from a uniformly accelerated nonrelativistic particle in a medium with a uniform decelerating electric or magnetic field are investigated theoretically, drawing comparisons to relativistic particles in a vacuum. The possibility of high-frequency emission from particles of velocity much less than the speed of light but approximately equal to the phase velocity of the medium electromagnetic waves is demonstrated: this implies preferential generation of overtones of the cyclotron frequency in a magnetic field, an effect with potential applications to microwave generation in low-effective-electron-mass semiconductors.