A novel scheme for guiding arbitrary buffer-gas cooled neutral molecules in a hollow optical fiber （HOF） using a red-detuned HEll mode is proposed and analysed theoretically. We give the electromagnetic field distribution of the HEll mode in the HOF and calculate the optical potential of an 12 molecule, and study the molecule guiding mechanism using a classical Monte Carlo simulation. Using a 6 kW input laser, an S-shape HOF with a 2 cm curvature radius for both bends, and an input molecular beam with a transverse temperature of 0.5 K and longitudinal temperature of 5 K, we obtain a guiding efficiency of -0.126% for the scheme, and the transverse and longitudinal temperatures of the guided molecular beam are 1.9 mK and 0.5 K, respectively.
In order to realize electrostatic Stark deceleration of CH radicals and study cold chemistry, the fifth harmonic of a YAG laser is used to prepare CH （A2△） molecules through using the multi-photon dissociation of （CH3）eCO, CH3NO2, CHzBr2, and CHBr3 at ~ 213 nm. The CH product intensity is measured by using the emission spectrum of CH （A2△→XeH）. The dependence of fluorescence intensity on laser power is studied, and the probable dissociation channels are analyzed. The relationship between the fluorescence intensity and some parameters, such as the temperature of the beam source, stagnation pressure, and the time delay between the opening of pulse valve and the photolysis laser, are also studied. The influence of three different carrier gases on CH signal intensity is investigated. The vibrational and rotational temperatures of the CH （Ae△） product are obtained by comparing experimental data with the simulated ones from the LIFBASE program.
We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.
An electrostatic trap for polar molecules is proposed. Loading and trapping of polar molecules can be realized by applying different voltages to the two electrodes of the trap. For ND3 molecular beams centered at -10 m/s, a high loading efficiency of -67% can be obtained, as confirmed by our Monte Carlo simulations. The volume of our trap is as large as ,-3.6 cm3, suitable for study of the adiabatic cooling of trapped molecules. Our simulations indicate that trapped ND3 molecules can be cooled from -23.3 mK to 1.47 mK by reducing the trapping voltages on the electrodes from 50.0 kV to 1.00 kV.
