Focusing limits of intense ultrafast laser pulses in a high pressure gas: road to new spectroscopic source

As a result of focusing ultrafast Ti:Sapphire laser pulses in a gas, a plas ma column is created. Its density does not exceed some limiting value as a result of the defocusing by the electrons resulting from multiphoton ioniza tion and the involvement of high order nonlinearities. The spectrum of the radiation from the excited species in the column has little contribution fr om the plasma continuum and the line broadening is less than that of the sp ectra radiated from a plasma generated by a long laser pulse, Thus, the spe ctroscopic source obtained using short laser pulses is an excellent source fur spectroscopy. (C) 2000 Published by Elsevier Science B.V.