Temperature induced normal state redistribution of B-1g spectral weight inunderdoped La2-xSrxCuO4

In electronic Raman Scattering experiments carried out on underdoped crysta ls of La2-xSrxCuO4 (La214) there is a depletion of low energy B-1g spectral weight relative to that measured in optimally doped (x approximate to 0.16 ) samples. In lightly underdoped (x approximate to 0.13) samples the deplet ion is independent of temperature for 20K < T < 300K. As the doping level i s decreased further, additional spectral weight is lost and, furthermore, i n the more heavily underdoped ( x approximate to 0.08) samples the depletio n at low energies also increases with decreasing temperature. Estimates are obtained for the magnitude of the pseudogap, E-g, and the onset temperatur e T*.