Production And Measurement Of Ultracold RbCs Polar Molecules

Atomic and molecular physics develop rapidly in rencet years arsing from laser cooling and trapping for cold atom, resulting to some important research interests in ultracold atoms and molecules, such as ultracold polar molecules. Ultracold polar molecules are of particular interest because they have pement electronic dipole moments, which mean that they are easy to be contronlled by extral field. Their dipole-dipole intramolecular interactions are long-range, ani so tropic, and tunable, resulting to some important applications, such as precision measurement, quantum calculation, many body problem and ultracold chemistry. The complicated rovibrational molecular structures provide some conditions for paralled calculation of quantum states, but also exclude the possibility of direct molecule cooling by laser cooling and trapping. The main methods to produce ultracold molecules are to associate ultracold atoms by laser field or magnetic field. In this paper, we constitute an experimental setup for photoassociative production and detection of ultracold RbCs polar molecules baesed ultracold rubidium and cesium atoms, use the atom trap loss technique and ionization spectrum technique to get the Photoassociation spectrum and ionization spectrum, study some related physical properties, such as atom collision property, molecular rotational constant and distortion constant, and molecular electric dipole moment.These are some innovative work in this thesis:1. We use dark MOT technique to increase cold atomic density in MOT with one order: cesium atomic density increases to6×10cm-3while rubidium atomics increases to6×1011cm-3, at the same time the collison rate decreases to half.This provides a foundation for production of ultracold RbCs molecules.2. We use modulation spectroscopy technique of atom fluorescence and resonant enhanced two photo ionization technique to realize the high sensitive detection of ultracold molecules in excited state and ground state, respectively.3. By using a robust non-modulation digital servo system to lock the laser frequency to atom-molecule transition, or even any absolute frequency in the laser frequency range. This frequency stabilization provides necessary technical support for the photoionization spectrum of ultracold RbCs molecules in ground state. 4. Based on high sensitive dection and frequency stabilization of work two and three, we observed the photoassociation spectrum and photoionization spectrum of ultracold RbCs molecules at long range and short range. This work provide experimental basis to produce the lowest rovibrational state RbCs molecules by one step photoassociative laser, whch is a new mechanism to produce RbCs molecules in the X(V=0,J=0) state.