Investigation of an Increase in Frequency of Scattered X-rays from a Silicon Single Crystal

摘要

Aims: X-ray scattered from a silicon single crystal was investigated. A new scattered line with increased frequency was observed. Study Design: In order to ascertain that the new modified X-ray line observed is not accidental, an inelastic scattering experiment has been performed, using a grazing incidence X-ray instrument with a resolution of 2x10-3. Place and Duration of Study: Institute of Physics, Bubaneswar, India, between Jan 2011 and Nov 2011. Methodology: In this experiment, X-rays are reflected from both the specimen and the focusing monochromator; which is known as reflection-reflection mode in double-crystal spectrometry (+1 -1). Incident radiation from an X-ray tube operated at 40 kV and 40 mA was used to obtain polychromatic CuK X-ray photons in the order of photon/s to observe a new scattering pattern from Compton effect caused excited plasmon (life time 10 -16 s) standing wave in the silicon crystal. Results: CuK X-rays scattered from silicon (333) crystal of 15 × 15 mm2 and 1mm thick, possess unambiguous existence of a new modified line with increased frequency. The new scattering possesses high momentum transfer kp > kc, as high as kp = 6.16 ± 0.01 ?-1 and (kp / kF)2 = 8.9. These findings are in agreement with the previous plasmon scattering results reported by various authors. The total cross section of this scattering is experimentally found out to be 2.95 ± 0.009 x 10-22 cm2/ electron and is inversely proportional to the third power of kp. Both theoretically calculated and experimentally observed wavelength shift data match well with each other. Conclusion: The new incoherent line was observed with the following major features: the energy of the new modified peak is greater than that of the Rayleigh peak; the new modified peak observed is narrower than the Compton peak for the same incident X-rays line.