ENHANCED HARMONIC-GENERATION IN EXTENDED MOLECULAR-SYSTEMS BY 2-COLOREXCITATION

Numerical simulations of high-order harmonic generation in the molecul ar ions H-2(+) and H-3(2+) show that two-color intense (I similar or e qual to 10(14) W/cm(2)) short(<1-psec) laser pulse excitation produces harmonics at large internuclear distances with larger efficiencies (i ntensities) at 6 U-p, 8 U-p, and 10U(p) energies than in single-atom s ingle-frequency excitation. The two-color excitation scheme creates ef ficient high harmonics by first ionizing electrons with a high-frequen cy laser pulse and accelerating them with lower frequency towards neig hboring atoms. Such two-color schemes should be useful for enhancing h igh-order harmonic generation in clusters.