Extracting the electron-boson spectral function a2F„v... from infrared and photoemission data using inverse theory

We present a method for extracting the electron-boson spectral function a2Fsvd from infrared and photoemission data. This procedure is based on inverse theory and will be shown to be superior to previous techniques. Numerical implementation of the algorithm is presented in detail and then used to accurately determine the doping and temperature dependence of the spectral function in several families of high-Tc superconductors. Principal limitations of extracting a2Fsvd from experimental data will be pointed out. We directly compare the IR and angular-resolved photoemission spectroscopy a2Fsvd and discuss the resonance structure in the spectra in terms of existing theoretical models.