Quartz vapor deposition onto

Materials. Biaxially oriented polypropylene (PP) films of 50 um thickness were obtained from 3M and have been described (2). PMDA-ODA (PI) was Kapton H polyimide from Dupont. Copper-plated PTFE films were obtained from Spire Corporation (Bedford, MA). They were prepared using the Ion Beam Enhanced Deposition (IBED) process in which a 100 nm thick Cu film was vapor-deposited onto a PTFE substrate in the presence of a beam of 400 eV Ar+ ions of 25 uA/cm2 (IQ). Shortly before SIMS analysis, the Cu film was removed slowly by peeling at 90° in ambient conditions. Metal-coated PI films were prepared by sputtering 50 nm Cr and 1 um Cu onto a 50 um thick Kapton film on both sides. Thermal annealing was performed in a vacuum chamber at 2xl0 6 torr using a quartz lamp as the heating source. The samples were held for 15 min at the desired temperature and then cooled down to ambient temperature inside the chamber for about 2 hours. Just prior to SIMS analysis, the metal films were peeled slowly at 90° and then immediately introduced into the vacuum chamber of the instrument. 

E. Saunders, M. Weinstein, A. I. Mlavsky, Radiant Energy Reactor Technique for the Deposition of SiC onto Quartz Filaments, Proc. Conf. Chemical Vapor Deposition of Refractory Metals, Alloys, and Comp., American Nuclear Society, Hinsdale, IL, 1967, pp. 1X1-21. 

The possibility that the chromophores of structures I, II and III might be distinguishable by their visible-ultraviolet spectra was examined. As shown in Figure 2, the spectrum of a polybutadiyne thin film, obtained by vapor deposition polymerization onto a quartz cell, is a nearly featureless continuum from 800 to 190 nm. This suggests that neither structure predominates and is in general agreement with a polydispersity as indicated by the breath of the infrared spectrum s aromatic bands. 

Ilie vapors of monomers deposit onto the surface of the substrate. The monomers with thermal energies diffuse on tlie surface and react with each other to form urea bonds between them. When the deposited quantities of monomers are balanced stoichiometri-cally, the addition polymerization proceeds sucoessivety. The thickness of the deposited layer is monitored by a quartz resonator. A schematic piciuic of the polymeiizalioo chamber is shown in Figure 3. 

Schafer and coworkers [23] developed a QCM-IL sensor for use as an artificial nose using the ubiquitous [C4Cilm][PFg]. The IL was spin coated onto the surface of a 10 MHz AT-cut quartz crystal with gold electrodes. The work specifically studied the response of the sensor to ethyl acetate. The deposition of the IL on the surface of the electrode decreased the resonance frequency of the QCM by 2017 Hz. Exposure to increasing amounts of ethyl acetate vapor produced a linear increase in frequency, which was attributed to a progressive decrease in viscosity of the IL upon adsorption of the analyte. The response time, given as the time to full saturation of the... 

Fig. 1. Schematic representation of vacuum furnace closed-cycle helium refrigeration system used for metal vapor microsolution optical spectroscopy, as well as conventional metal vapor-matrix isolation experiments. (A) NaCl or Suprasil optical window, horizontal configuration (B) stainless steel vacuum shroud (C) NaCl or Suprasil optical viewing ports (D) cajon-rubber septum, liquid or solution injection port (E) gas deposition ports (F) vacuum furnace quartz crystal microbalance assembly. With the optical window in a fixed horizontal configuration, liquid or solution sample injection onto the window at any desired temperature in the range 12-300 K is performed in position 1A, metal deposition is conducted in position IB, and optical spectra are recorded in position 1C see Procedure).

The wet disks are immediately immersed into the vapor of refluxing isopropanol. Once they reach the reflux temperature, as noted by a reduction in the rate of alcohol condensation on the disks, they are removed into the room air where they rapidly become dry and slowly cool to room temperature. At this point, the disks are individually weighed to the nearest 0.1 mg. The disks are then loaded into a metal tray with large circular regions on their bottom faces exposed and the tray placed in the load lock of a vacuum chamber. The load lock is pumped to about 10 torr and then the tray is translated into the chamber and the load lock sealed off from the chamber. The chamber is pumped to about 10 torr with a cryopump. The major residual gas is water from the rotatable rubber seal used between the evacuated space in the chamber and the water flow path into and out of the rotatable copper crucible mentioned below. Titanium vapor is sublimed from a Ti ingot by bombardment with about 8 keV electrons while the periphery of the ingot is cooled by sparse physical contacts with the water-cooled copper crucible in which it rests. The Ti vapor condenses in the line of sight from the source onto the exposed bottoms of the disks. The thickness of the deposited titanium, is monitored by a calibrated quartz crystal balance close to the quartz disks. Typically (iji 5 x 10 cm. 

Intensive research effort has been focused on using nanoscale structures to significantly improve the performances (sensitivity, selectivity, response and recovery speed) of the SAW sensors. Liu et al. [39] reported that dynamic chemical vapor SAW sensors have been developed by depositing electrospun polyethylene oxide nanofibrous membranes on the surface of ST-cut quartz the response time of the sensors was 5 min (Fig. 11.2a). Lin [42] constructed a SAW humidity sensor by casting polyaniUne/poly(vinyl butyral) nanofibers on SAW resonator the as-prepared sensor could detect 0.5 % relative humidity in 1 s. Electrospun poly(vinyl pyrrolidone) (PVP)/LiTa03 composite nanofibrous membranes were coated onto the surface of SAW electrode to assay H2 the results indicated that the sensors sensitivity, response time, and recovery time could be remarkably improved and reached 1 %, 120, and 200 s by regulating the electrospinning parameters [43]. 

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