Investigation of Cu 𝐾𝛽 emission spectrum under high intense laser excitation

Abstract

Since the invention of high power femtosecond lasers as technology advances, they have been used in various fields such as laser machining, X-ray generation, investigating ultrafast phenomena such as metal insulator transition of Mott insulators. Understanding the interaction of the laser with metals, are critical for many applications. Therefore, we made an experiment to study the spectrum of X-ray emission line during laser-matter interaction. Two experiments were carried out. First, we measured the XANES data of Ni and compared with the reference data to show capability of the X-ray spectrometer used here. Electric structures (3d and 4p energy level structure) shown in XANES are identical to reference data. Second, we obtained fluorescence spectrum near the Cu 𝑘𝛽 laser induced plasma X-ray obtained from the Cu target. As a result, it was confirmed that the 𝑘𝛽2,5 lines were shifted by 4eV towards high energy we speculated that. The reason for this is that the energy level shifts due to the Stark effect due to the strong electric field generated by the laser, or population of empty levels near Fermi level. In addition, as the intensity of the laser increased, we found that the peak shape of 𝐾𝛽1,3 and 𝐾𝛽2,5 became broader. This is caused by the enhanced stark broadening by the plasma produced during the interaction under stronger laser intensity.