A numerical calculation method for the optical trapping force which is appropriate for single lensed fibre trapping (SLFT) is proposed. The piconewton optical trapping forces on a yeast cell in SLFT as a function of the position along two horizontal orthogonal axes are measured experimentally by static and dynamic methods, respectively. The order of magnitude and the characteristics of the theoretical trapping force curve calculated by our method are the same as those of the experimental measurement curve. The theoretical and experimental results for the angle of inclination of the fibre probe also coincide with each other.
Three different coating materials for lowering the H-atom recombination probability on stainless-steel chamber walls were investigated and the results were compared. SiO2 films prepared by natural oxidation of perhydropolysilazane, polytetrafluoroethene (Teflon) films, and H3PO4 coated SiO2 films were used as coating materials. Among them, the SiO2 film was found to be the most useful for this purpose. The densities of H atoms produced by catalytic decomposition of H2 on heated tungsten surfaces were measured by a vacuum-ultraviolet laser absorption technique under various conditions. The H-atom density increased by one order of magnitude with SiO2 and Teflon coating, the former of which is easier to use and more economical. No further increase in H-atom density was observed when the chamber was coated with H3PO4. SiO2 films prepared from perhydropolysilazane were not etched by H atoms. Quadrupole mass spectrometric analysis showed that the production of either SiH4 or H2O is extremely minor. No surface etching was confirmed by x-ray photoelectron spectroscopy (XPS), either. Scanning electron microscopic (SEM) observations showed that the SiO2 films are not porous even after H-atom exposure. It is also suggested that cooling of the chamber walls is important to preserve the H-atom density.
The mechanism of catalytic chemical vapor deposition (Cat-CVD) processes for hexamethyldisilazane (HMDS) and trisdimethylaminosilane (TDMAS), which are used as source gases to prepare SiNx or SiCxNy films, was studied using three different mass spectrometric techniques: ionization by Li+ ion attachment, vacuum-ultraviolet radiation and electron impact. The results for HMDS show that Si–N bonds dissociate selectively, although Si–C bonds are weaker, and (CH3)3SiNH should be one of the main precursors of deposited films. This decomposition mechanism did not change when NH3 was introduced, but the decomposition efficiency was slightly increased. Similar results were obtained for TDMAS.
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