Abstract
The goal of this experiment is to study the spectroscopy of ultracold potassium atoms. We trapped approximately 〖10〗^7 (_^39)K atoms by magneto-optic trap (MOT) and the temperature of ultracold (_^39)K atoms reached 0.5 mK ~1 mK. Three spectroscopies: the fluorescent spectroscopy of the D_2 line of ultracold (_^39)K potassium atom, the trap loss spectroscopy of the D_1 line, and the trap loss spectroscopy of the molecular photoassociation. The fluorescent spectroscopy of ultracold atoms was performed by changing the frequency of AOM to access the hyperfine spectroscopy of the D_2 line and the result was in a good agreement with the measurements of the previous experiments. The trap loss spectroscopy of the molecular photoassociation was to use a Ti-Sapphire laser with 200 mW output power to excite the ultracold atom pair. The trap losses signal are due to the energy release and the increase of atomic kinetic energy. We observed the hyperfine structure and the linewidth of the spectrum is about 10 MHz to 15 MHz. The D_1 spectroscopy was also used to calibrate the frequency of our Ti-Sapphire laser. The photoassociation spectroscopy was performed in the regions where the excited levels near the D_1 and D_2 transitions. Around the D_2 line, we obtained a trap loss of about 13 %. In the other hand, the photoassociation spectroscopy is observed with 6 % trap loss around D_1 line. The results show that it is possible to form ultracold potassium molecules by photoassociation. It could be used to study the collision of ultracold atoms and ultracold molecules in the future.