We report the generation of short-wavelength, high-order harmonics of intense laser radiation from atom clusters. Clusters containing about 103 atoms are produced in a high-pressure gas jet. We show them to be a unique nonlinear medium. Compared with monomer gases they yield a higher appearance intensity for a given harmonic order, stronger nonlinear dependence of harmonic signal on laser intensity, higher-order harmonics, and reduced saturation of the harmonic signal at high laser intensity.
© 1996 American Physical Society
T.D. Donnelly, T. Ditmire, K. Neuman, M.D. Perry, R.W. Falcone, "High Order Harmonic Generation in Atom Clusters," Phys. Rev. Lett. 76, 2472 (1996). doi: 10.1103/PhysRevLett.76.2472