We demonstrate the use of Fourier transform infrared (IR) spectroscopy for midinfrared emission measurements following x-ray or electron excitation. Spectra from an InAs low band-gap semiconductor film, which emits in the IR from 3000 to 3400 cm−1, are presented. There is good agreement between the present results and previously published laser-excited spectra. Using focused beams, it should be possible to perform sub-diffraction-limited IR imaging. In addition, simultaneous structural and electronic analysis could be performed using the x-ray or electron excitation probes.