ON AMPLIFICATION OF RADIATION EMITTED FROM THE EXCITED AUTOIONIZING STATE OF THE H-2 MOLECULE IN THE PRESENCE OF INCOHERENT PUMPING TO THE LOWEST AUTOIONIZING STATE

We have shown that the amplification without population inversion (AWO PI) from the fu st excited autoionizing (AI) state of the (1)Sigma(g) symmetry of the H-2 molecules can be obtained when the lowest AI state of the (1)Sigma(g) symmetry is pumped incoherently. We have considere d a resonant two-photon transition scheme from the ground X(1)Sigma(g) (v = 0; j = 1) state to the ionization continuum embracing the two AI states (the lowest and the first excited autoionizing states) of the (1)Sigma(g) symmetry via the resonant intermediate B(1)Sigma(u) (v = 4 , j = 2) level. The effect of two-photon near-resonant autoionizing ch annels via the near-resonant rovibrational levels of the B(1)Sigma(u) state has also been considered. We have found that the gain can be obt ained in different spectral regions corresponding to the resonances wi th the lowest and first excited AI states from the inter mediate level s of the B(1)Sigma(u) state. The inherent coherence between two AI sta tes due to the configuration interaction coupling via the common conti nuum has been found to have a significant effect on the amplification process, which occurs around all the resonance frequencies connecting this AI state with the intermediate levels. This gain can be significa ntly modified by increasing the coupling strength of this excited AI s tate with the continuum, Moreover, the gain from the excited AI state remains unaffected by the damping caused by incoherent pumping to the lowest AI state. It has also been shown that the persistence of invers ionless gain from the excited AI state is shorter than that from the l owest Al state. The presence of close-lying near-resonant rovibrationa l levels leads to the increase in gain around the resonances with two AI states from the B(1)Sigma(u) (v = 4, j = 2) level. The advantages o f this type of scheme are: i) AWOPI can be obtained from an excited AI state although it has not been pumped and ii) the amplification obtai ned from the excited AI state is almost unaffected by the distortion c aused by incoherent pumping to the lower AI state.