The basic definition of Fourier Transform Infrared measurement (FTIR) is "the measurement of infrared radiation from a source with a single frequency". The simplest description of FTIR is "a microwave source comprising a source having a frequency which undergoes a phase shift when transformed into or emitted from a microwave cavity". The name "FTIR" was first used in 1958. A more accurate description is "the detection of changes in radiation heat patterns resulting from the interaction of a source and a chosen background". The primary objectives of using an instrument like FTIR for biomedical research are: to determine the physical structure of biological samples; to characterize molecular processes; and to detect a wide range of physical processes occurring in real systems.
"I am looking for DSP Si wafers to use as substrates (or matrices) in FTIR measurements. For this, I need the wafers to be as transmissive in the mid-IR as possible. DSP intrinsic Si is about 60% transmissive. Do you sell any anti-reflective coatings on the wafers to make them more transmissive in this regions? Do you recommend any of your products besides the DSP wafers for this purpose?"
UniversityWafer, Inc. Quoted:
6” DSP wafers,Work well for IR are spec’d at:
Resistivity: 10 – 20 Ohm cm
Thickness: 625± 25um
Contact us for pricing.
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Below are just some recent silicon wafer specs used by our clients for FTIR Measurments. They are high-quality, inexpensive substrates.
Si Item #1583 - 100mm P/B <100> 0.001-0.005 ohm-cm 500um SSP Prime with 300nm of Thermal Oxide
Si Item #452 - 100mm P/B <100)> 0-100 ohm-cm 500um SSP Test Grade
Definition. In general, the measurement of infrared radiation from a sample must comply with the specific measurement procedures specified in Standard No. 639, Standard Benchmark for Imaging Variances. There are three broad categories of infrared spectroscopy measurement techniques. The first category, Colorimetric Spectroscopy (C Spectroscopy), uses color filters to identify and quantify amounts of various substances as well as any color changes within those substances. The other two categories, Diode Spectroscopy and Gas Chromatography, use different methodologies to measure the composition of a sample, but employ the same filter combination to achieve the result.
Spectroscopy. This technique measures the amount of infrared radiation emitted or absorbed by a sample. The most common device for this is a scanning plate such as a quartz plate or an optical media reader. Since the emitted light comes from charged particles, the dominant light is red, which can be easily detected on a periodic basis by a spectroscopic spectrophotometer.
Diode Crystallography. A diode crystal is formed by crystal diffusion after it is deposited on a substrate. The impure gas or liquids that are present when the crystal forms may have different concentrations. When the applied voltage and current are applied, changes in the temperature of the liquid or the applied electric field lead to differences in the concentrations of the lighter chemicals present in the crystal. Due to this, there may be peaks and valleys in the electric field resulting in differences in the concentrations of various compounds, such as oxygen, in the bulk of materials deposited on the crystal. As a result, this technique produces a record of the structure of crystals upon which the applied voltage and current are measured.
Multilayer Films. There are many applications in which the observation of single wavelengths or a collection of wavelengths at different wavelengths is crucial for determining properties of interest. Examples include polarimetry, mass Spectrometry, and nondestructive testing. In the case of polarimetry, a thin film is applied to a substrate with correlated polarizations. The thickness of this thin film is controlled, and a peak intensity profile is then extracted from the multilayer film by exposing the film to varying voltages and intensities.
H Thioure Transient Transients. An H Thioure Transient instrument is a very fast and accurate measurement method but is less sensitive than other methods. A transient probe consists of two mirrors, one with a positive charge electrode, the other negative. When the mirrors are placed close to each other and an electrical current is passed through them, they each emit photons as they switch places.
Figure 2: Transient Solutions. In a Fourier Transform Infrared measurement, a high-frequency electric field sweeps through a medium, such as a quartz plate or a wafer of plastic. The frequency of passing light through the Transient Solution causes excited atoms to emit radiation. This is the basis for measuring the total absorption as well as the total mobility of molecules in the solid.
For better results, the h-factor needs to be calculated and this is done with the aid of Laser irradiation Spectroscopy (LIS). A Transient Solution, also known as a LIS spectra passes through a series of alternating Fresnel angles. For the purposes of this discussion, we restrict our discussion to the single-particle absorption and mobility properties of H Thioure Transient Solutions.