H_2^+分子谐波发射的空间分布

Spatial distribution of molecular harmonic emission from H_2^+

理论研究了H_2^+分子发射高次谐波的空间分布情况。结果表明:分子谐波主要发生在两个H核附近。当核间距离较小时,两个H核发射谐波强度几乎一致。核间距离增大,正向H核发射谐波强度大于负向H核。随着空间非均匀激光场的引入,H_2^+分子在较小核间距离时,负向H核发射谐波强度略大于正向H核;在较大核间距离时,正向H核发射谐波强度大于负向H核。随着空间非均匀激光场引入位置从负向移动到正向(-100 a.u.到100 a.u.),正向H核发射谐波强度逐渐减小。通过叠加谐波可获得脉宽在66 as和62 as的超短阿秒脉冲。

The spatial distribution of high-order harmonic generation from H2＋ molecules is theoretically investigated. Results show that the molecular harmonic emission mainly occurs around two H nuclei. When the internuclear distance is relatively small, the harmonic intensities of the two H nuclei are almost the same. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus with the internuclear distance increasing. With the introduction of the spatial inhomogeneous laser field, the harmonic intensity emitted by the negative-H nucleus is slightly higher than that of the positive-H nucleus when the internuclear distance of H＋ molecules is relatively small. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus when the internuclear distance is larger. As the spatial position of the space inhomogeneous laser field shifts from negative to positive（ from -100 a.u. to 100 a.u.）, the harmonic intensity emitted by the positive-H nucleus decreases gradually. The ultrashort attosecond pulses with durations of 66 as and 62 as can be obtained by superposition of harmonics.