The morphology of the porous silicon was measured by scanning electron microscopy (SEM) using a FEI XL30 SEM (FEI, Hillsboro, OR, USA) operating in secondary electron imaging mode. To avoid sample charging MGCD0103 price anomalies, the porous Si samples were metalized with a thin layer of gold prior to the SEM analysis. The pore size and the porosity oscillations of the rugate filter structure were evaluated with this analysis. Measurement of
porous silicon degradation The pSi degradation was studied using a custom-designed transparent flow cell system with a total volume of 4.5 mL (including connections). The 1:1 (v/v) ethanol 0.5 M carbonate/borate buffer solution (pH 10) was flowed in at the bottom of the sample using a peristaltic pump at a rate of 10 μL/s and room temperature (20 ± 1°C). Ethanol was included in the buffer to improve the permeation of solution into the pores and reduce the formation of bubbles that could affect the subsequent image analysis. The degradation of the fpSi and pSi-ch samples was monitored by obtaining reflectance spectra (spectrophotometer) and photographs P005091 cell line (digital camera) every 5 min through the front cover of the flow cell until after complete degradation had occurred (300 min). To obtain both measurements
repeatably during the same experiment, the optical paths for the reflectance probe and the camera were located in front of the flow cell along the sample surface normal as is shown in Figure 1. The sample was illuminated by means of a diffuse axial illuminator coupled to a Fiber-lite MI-150 (Dolan Jenner, Boxborough, MA, USA) light source with an approximate color temperature of 3,000 K mounted between the flow cell and the camera. A beam splitter (Thorlabs CM1-BS2
Cube-Mounted Non-Polarizing Beamsplitter, 50:50, 0.7 to 1.1 μm; Newton, NJ, USA) between the diffuse Amylase axial illuminator and the flow cell also allowed measurement of the reflectance spectrum over 400 to 1,000 nm with the reflectance probe of a fiber optic https://www.selleckchem.com/products/ganetespib-sta-9090.html spectrophotometer (Ocean Optics USB-2000-VIS-NIR). The reflectance probe was rigidly fixed to the beamsplitter via lens tubes containing a focusing lens. Figure 1 Photograph of equipment for simultaneous acquisition of photographs and reflectance spectra. 1 flow cell containing pSi sample, 2 beam splitter, 3 reflectance probe connected to fiber-optic spectrophotometer, 4 diffuse axial illuminator with tungsten light source, 5 camera, 6 pSi sample, and 7 spectrophotometer. Inset: image of the pSi sample as captured by the digital camera. The reflectance spectrum acquisition was controlled by Spectrasuite software (Ocean Optics, Inc.). The position of the rugate reflectance peak and the FFT of the portion of each reflectivity spectrum that displayed Fabry-Perot interference fringes were calculated using custom routines in Igor (Wavemetrics, Inc., Portland, OR, USA).