PN 350-025004-09
Page | 6
Performance Verification
1. With the accessory removed from the sample compartment, collect an open beam background
spectrum.
2. Place the MIRacle accessory in the instrument per installation steps described on page 4.
3. Collect a spectrum of the MIRacle ATR using the same collection parameters as used to collect the
background spectrum.
The following are the % transmission values the accessory should achieve with different crystal
configurations at 1000 cm
-1
(with the exception of the Si value which is shown at 2000 cm
-1
).
ZnSe Single Reflection ATR Plate Greater than 22%T
Ge Single Reflection ATR Plate Greater than 25%T
Diamond w/ZnSe lens Single Reflection ATR Plate Greater than 25%T
ZnSe 3-Reflection ATR Plate Greater than 12%T
Diamond w/ZnSe lens 3-Reflection ATR Plate Greater than 12%T
Specular Reflection Plate Greater than 20%T
Diamond w/ZnSe lens 9-Reflection ATR Plate Greater than 6%T
The MIRacle ATR throughput spectra appear different and show different spectral features depending
upon the crystal material. One notable feature is the spectra range cut-off (where IR throughput goes to
zero) at the long wavelength end of the spectrum (near 400 cm
-1
).
In the spectrum shown for the ZnSe crystal plate the long wavelength cut-off is about 520 cm
-1
. Also
shown in this spectrum is that the IR throughput is about 32% at 1000 cm
-1
.
A feature in the diamond ATR crystal plates and present in the spectrum shown on the following page is
known as the diamond phonon broad IR absorbance bands, which appear, between 2600 and 1900 cm
-1
.
This is a normal absorbance present in all diamond spectra. This feature ratios well in a typical sample
spectrum. It does, however, reduce the signal-to-noise ratio (SNR) in this spectral region.
If your accessory does not meet this minimum transmission level, please contact PIKE Technologies.
Before calling, please record the serial number located on the label on the back of the MIRacle base
optics assembly.
NOTE: IR throughput performance of your accessory will decrease slowly over time as the lens surface is
exposed to the environment and due to normal wear from cleaning the ATR surface. Contact PIKE
Technologies for information about MIRacle Crystal Plate reconditioning services when throughput drops
below a usable level.
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