If the bands have significant intensity (i.e. The spectrum should show weak bands from water vapor (3000-3500 cm -1, 1600≡750 cm -1 and below 400 cm -1) and CO 2 (twinned peak around 2350 cm -1). Obtain a background IR spectrum by clicking the icon B in the upper left corner of the screen. Allow the sample compartment to purge for some time. Make sure that the lid of the sample compartment is closed. It can be changed to absorbance units by clicking the mouse.īackground spectrum. The bottom half of the window is for selecting the vertical axis (%T is default). In the measurement program, go to Measurement-Parameter-Standard. You can choose whether your spectra are plotted with the y-axis as absorbance or as % transmittance (%T). The resolution is set to 4 cm -1 as default. The menu pops up with scan times: 16 (default). In measurement program: go to Measure-Parameters-Standard. To change the range, go to Settings-measurement range. For most of the applications, the suitable range is thus 400 to 4000 cm -1. Note that unless the instrument purge is quite rigorous, there will be considerable spectral interference from water vapor below 400 cm -1. A better resolution usually leads to very noisy spectra under those conditions. This will be good enough for most standard measurements. The preset parameters are 16 scans with 4 cm -1 resolution and a measurement range of 250≤000 cm -1. Go to ( Measure-parameter) and read in the default file (default.pr). You will first have to use the spectra measurement program. Start the spectra manager from the desktop screen on the computer. NOTE: PLEASE DO NOT OVERWRITE THE DEFAULT FILE SETTINGS! Make sure that the IR spectrometer has been turned on. Pay attention to the installation environment.1.Detector saturation is more likely to occur.The number of accumulations can be increased to improve the S/N ratio.In most practical uses, the maximum exposure time is 4 – 5 seconds.A background measurement must be taken before each sample measurement.Since the characteristics of a CMOS detector are very different from a Charge-Coupled Device (CCD) detector, which is standard in the NRS and RMP series of Raman spectrometers, the following should be taken into consideration: The PR-1w Palmtop Raman Spectrometer uses an uncooled Complementary Metal Oxide Semiconductor (CMOS) sensor as its detector. Increasing the number of accumulations will increase the measurement time but also improve the S/N ratio. If a sample has weak Raman scattering, increasing the exposure time will result in a better Raman signal. Raman spectrometers enable the control of data acquisition by adjusting the exposure time and the number of accumulations that are averaged together for a final spectrum. If you are concerned with damaging your sample, start with the laser at low power and slowly increase the laser power until you have a good Raman signal with no sample degradation. As a result, the Raman signal will increase when a higher laser power is selected however, increasing the laser power can potentially burn your sample.
The Raman signal (I) is directly proportional to the power of the laser (mW). The Palmtop Raman spectrometer (PR-1w) contains a 785 nm laser that has three different power settings: Low/Medium/High (5 mW/25 mW/50 mW, respectively).