Optical emission spectra from laser ablation of graphite at 266 nm and 1064 nm under a magnetic field

Optical emission spectra were measured during laser ablation of graphite at 266 nm and 1064 nm at fluences of 1.7-12.2 J/cm(2) with or without a magnetic field of similar to 0.1T. In the presence of magnetic field, the intensity distribution of C, C+, and C2+ emission lines varied considerably and some of the emission lines which originated from higher excited states became obscure. In addition, the C-2 Swan band emission appeared, particularly during 1064 nm laser ablation. These changes in emission spectra are explained in terms of the promotion of ionization of C and C+, formation of C-2, and deexcitation of electronically excited states, resulting from enhanced collisions between ablated species due to cyclotron motions under a magnetic field. We will discuss the formation and excitation of C-2 and C2+, and deexcitation of electronically excited C+ and C2+.