Determination of the effective electron mass in an optical field from the measured emission spectrum of ultrarelativistic electrons at a laser focus
Goreslavskii S. P. , Narozhnyi N. B. , Shcherbachev O. V.
By measuring the emission spectrum of an electron beam as it interacts with a focused laser pulse, one can directly observe a frequency shift of the radiation caused by a dependence of the effective mass of the electron on the .intensity of the optical field. © 1995 American Institute of Physics.