Knowledge Bank

This paper reports our new results about the generation of stimulated emission located at 3.14 and $3.16\mu m$ by two-photon pumping within suptising wide wavelength region. It is interesting to find those emission corresponding to the transition of 5p-3d of K were obtained from a heat pipe oven throughout the scanning output from 6250 to 6950 {\AA} of a pulse dye laser pumped by a nitrogen laser. Moreover, at the long wavelength end of the above mentioned scanning region, even appeared sharp peaks. Fig.1 shows the dependence of relative lasing energy on the pumping wavelength. We judged that the wide peak in Fig.1 was the stimulated emission following the photodissocition of $Ke$ pumped by two-photon, and the sharp peaks were that of K which were excited by the resonant collissions energy transfer between K in the ground state and $K2$ in an excited state closely below the dissociationenergy of a high- lying grade state. Since the energy difference from the bottom of $X1\Sigma g+$ of $K2$ to this excited level, which is possible to dissociate into two seperated atoms of 4s and 5p, is about $E=28920cm-1$, the two-photon energy at the most parts of the scanning region is beyond 3. Therefore, the 5p lever of K is possible to be populated, and the stimulated emission of 5p-3d is obtained as shown in Fig.2. However, at the long wavelength end, the two-photon energy is slightly smaller than E. So $K2$ excited from the lowest vibrational level of $X1\Sigma g+$ state may collide with K and resonantly transfer the excited energy to it. Thus the 6p level of K is possible to be populated and the sharp peaks were observed. The mechanism was demonstrated by the effects of the experimental temprature and pressure