Abstract: A laser based tunable high resolution ESCA (Electron Spectroscopy for Chemical Analysis) system in which harmonics of a subpicosecond laser source are used to carry out core level photoemission is provided wherein photon energies tunable to 80 eV have been achieved and energies up to 150 eV or more are possible. The harmonic light is of extremely narrow bandwidth and spectrally bright which can be focussed by using reflective optics of gratings to an extremely small spot of well below one micron to permit high spatial resolution. When used in conjunction with appropriate electron objects, high resolution chemically sensitive mapping of device-size features is possible.