EFFECT OF AMBIENT RELATIVE HUMIDITY AND SOAKING TIME ON THE FORMATION OF OCTADECYLTRICHLOROSILANE COATINGS ON BOROSILICATE GLASS SUBSTRATES FOR ALKALI-METAL VAPOR CELLS

The most sensitive spin-exchange relaxation-free (SERF) magnetometer generally requires a working temperature greater than 100∘C. To date, octadecyltrichlorosilane (OTS) coating is one of the best candidates for this temperature range. However, the performance and consistency of the OTS coatings within the alkali-metal vapor cells are still poor. In this paper, the formation of OTS coatings on borosilicate glass (BG) substrates was investigated. The effects of ambient relative humidity (RH) on the formation of OTS coatings were examined by atomic force microscopy (AFM) and contact angle measurement. The results showed that 75[Formula: see text] RH can improve the order of the OTS coatings and reduce the root mean square (RMS) roughness of the OTS coatings. Under three different ambient RHs, the soaking time of OTS molecules should be greater than 60[Formula: see text]min to form complete OTS coating.

Резонансы когерентного пленения населенностей в стеклянных ячейках с парами атомов цезия, изготовленных методом индукционной сварки

The paper discuss the possibility of using induction welding for creation of spectroscopic cells. This approach improves the optical quality of windows, increase the repeatability of manufacture, and simplify the creation of spectroscopic cells filled with alkali metal vapor. Described technique can be used in the rapidly developing applications, such as quantum frequency standards based on coherent population trapping (CPT). The paper presents a description of the design of cells with flat windows, the results of studies of the spectroscopic properties of the obtained cells and the results of work with the obtained cells used as part of the frequency standard.

Study on the phase evolution and element migration of vanadium oxide during the nitridation process

In this paper, a series of nitriding experiments were carried out to investigate the phase evolution and element migration in the nitriding process. The results show that it undergoes a low temperature reducing stage firstly. High valent vanadium oxides are reduced to V2O3 between room temperature and 770 °C. In Ar atmosphere, V2O3 reacts with C to form VC in the temperature interval of 770 °C∼1080 °C. In N2 atmosphere, V2O3 reacts directly with N2 and C to form VN in the interval of 670 °C∼1050 °C. During 1050 °C∼1270 °C, part of the VN obtained in the previous reaction stage will react with C to form VC. High temperature is beneficial to the removal of impurity element sulfur. The volatilization of alkali metal elements in the pellet mainly occurs between 670 °C and 1270 °C. However, there are about 20% of sodium and potassium remain in the nitriding product. The volatile alkali metal vapor would react with other gases at the furnace cover to form a white sediment and deposits on the cover. The sediment mainly consists of Na2CO3, K2CO3, Na2SO4, K2SO4, KCl, etc.

Adhesion Effect on the Hyperfine Frequency Shift of an Alkali Metal Vapor Cell with Paraffin Coating Using Peak-Force Tapping AFM

We have investigated the adhesion effect on the hyperfine frequency shift of an alkali metal vapor cell with paraffin coating using the peak-force tapping AFM (atomic force microscopy) technique by developing a uniform and high-quality paraffin coating method. We observed a relatively uniform temperature field on the substrate can be obtained theoretically and experimentally with the closed-type previse temperature-controlled evaporation method. The roughness and adhesion of the coating surface as low as 0.8 nm and 20 pN were successfully obtained, respectively. Furthermore, the adhesion information dependence of the topography was investigated from the force spectroscopy, which indicates that the adhesion force jumped on the edge of the particles and stepped but remained constant above the particles and steps regardless of their height for paraffin coating. Finally, we can evaluate the relaxation and the hyperfine frequency shift of an alkali metal vapor cell through accurately calculating the surface adsorption energy of the paraffin coating from peak-force tapping information. This finding is crucial for improving the sensitivity of the atomic sensors through directly analyzing the adhesion effect of the paraffin coating films instead of measuring the relaxation times.