Shimadzu IRAffinity-1, Instruction Manual

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Chapter 1 Principles, Description, and Functions of the IRAffinity-1
1-12
IRAffinity-1
The beam from the light source (1) is reflected once by the spherical mirror (2), then converged in
the aperture (3) position. The beam which has passed through the aperture is reflected by the
collimator (4), made into parallel beam, then introduced into the interferometer (5). The IRAffinity-1
has the Michelson interferometer whose incident angle is 30 degrees.
The infrared beam introduced into the interferometer is divided by the beam splitter into the moving
mirror (8) and the fixed mirror (9). Each reflected beam becomes the interfered beam on the beam
splitter, and goes to the converging mirror (13) after reflecting by flat mirrors (10) and (11). This
fixed converging mirror is equipped with the auto alignment function which always realizes the
maximum interference efficiency.
By the converging mirror (13), the parallel infrared interfered beam makes a light source image in
the center of the sample compartment. Usually, set a sample in this center of the sample
compartment, then measure it. The beam which has passed through a sample is reflected by the
converging mirror (14), converged in the detector (15), then detected as the interferogram.
The aperture size is automatically selected in accordance with measurement and resolution. The
aperture can be set manually without regard to measurement and resolution. For the details, refer
to the Help document included in the software.
The image size in the sample compartment in each resolution is as follows (when the standard light
source is used).
When (1) thin films are measured by transmittance method, (2) samples are measured by KBr-
pellet method, or (3) liquids sample are measured with liquid cells with high-transmittance windows
such as KBr or NaCl, "A/D error" may occur with 2.0 mm/sec as mirror speed and "Open" as
aperture size. The reason is that the output from the DLATGS detector becomes higher and
exceeds the capacity of the A/D converter. Set "auto" or smaller aperture. On the other hand, when
samples are measured with "Open" aperture using an ATR or Diffuse reflectance accessory, the
quality of the obtained spectra may be improved because the sensitivity of the detector becomes
higher within the capacity of the A/D converter.
When using an accessory such as KBr tablet which limits the image size in the center of the sample
compartment, the optical aperture effect is obtained. As a result, peak wavenumber deviation way
occurs depending on the existence of an option. To cope with this, execute background
measurement by using a same option (without sample) used in sample measurement.
Use 3.0, 2.1 or 1.5 as Aperture to scan background and sample spectra.
1.5.4 Light Source
The ceramic light source of high luminance and long life is used as standard.
Resolution Mirror speed Aperture Image size
4 - 16 cm
−
1
2.8 - 9 mm/sec Open Approx. 13 mm
4 - 16 cm
−
1
2.0 mm/sec 4.3 Approx.
φ
9.7 mm
2 cm
− 1
2.0 - 9 mm/sec 3.0 Approx. φ 6.8 mm
1 cm
− 1
2.0 - 9 mm/sec 2.1 Approx. φ 4.7 mm
0.5 cm
−
1
2.0 - 9 mm/sec 1.5 Approx.
φ
3.4 mm