PerkinElmer Spotlight 150, User Manual

Page: 51 / 107

Preparing Samples . 51
Techniques for Preparing Samples for
Transmission Measurements
This section describes some useful techniques for preparing various types of samples.
Flattening Solids
Flattening samples by pressing or squeezing often enables you to make thick samples thin
enough to give good infrared spectra. As the samples are usually quite small, only moderate
force is necessary.
Rolling with the roller knife
The roller end of the roller knife provided in the microsampling tool is one of the simplest
and most effective devices for flattening samples. It is especially useful for flattening fibers
or particles.
You can treat different types of sample in different ways:
• If the sample is soft, you can roll it on a small salt window.
• If the sample is hard, you can roll it on a hard surface, such as glass or metal. A flat,
black cap from a jar makes a good surface for rolling a light-colored sample.
•
If you roll the sample on a small, flat piece of metal you can view it and collect spectra
in reflectance mode. Samples rolled on windows transparent to infrared can be
examined in transmittance.
• If you flatten fibers on a glass microscope slide, they can then be peeled off and
mounted either on a window or over the aperture for the microscope slide.
Squeezing with a pellet press
You can squeeze samples between the polished anvils of a KBr pellet press without KBr. To
collect the spectra use one of the following methods:
•
Peel the flattened sample off the anvil with a probe or knife and place it on a sample
mount. Collect the transmittance spectrum.
•
Leave the sample on the polished anvil and collect the reflection spectrum. Use a clean
area of the anvil as the reference.
Using a diamond anvil cell
See
Diamond anvil cell
on page 53 for information on flattening samples with a miniature
diamond anvil cell.