Shimadzu IRAffinity-1, Instruction Manual

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4-4
IRAffinity-1
Chapter 4 Operations
This section describes precautions for scan parameters.
4.3.1 Mirror Speed, Resolution and Aperture Setting
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 details, refer to
the Help document included in the software.
The aperture size is as follows.
When (1) thin films are measured by transmittance method, (2) samples are measured by KBr-
pellet method, or (3) liquid samples 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
φ
3 mm 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 occurs depending on the selection of an option. To cope with this, execute background
measurement by using the same option (without sample) used in sample measurement.
Use 3.0, 2.1 or 1.5 as Aperture to scan background and sample spectra.
Resolution Mirror speed Aperture
4 - 16 cm
−
1
2.8 - 9 mm/sec Open
4 - 16 cm
− 1
2.0 mm/sec 4.3
2 cm
− 1
2.0 - 9 mm/sec 3.0
1 cm
−
1
2.0 - 9 mm/sec 2.1
0.5 cm
−
1
2.0 - 9 mm/sec 1.5
4.3 Scan Parameters