Experimental Techniques

The majority of beamtime is currently used for spectromicroscopy experiments either in transmission or reflection mode, for chemical mapping using the XY-stage of the microscope. There is also an MTEC 300 detector available for Photoacoustic Spectroscopy (PAS), with an additional micro-PAS detector currently being developed for use with the IR microscope.

The Mid IR beamline has several accessories for the Bruker Hyperion microscope that allow additional experimental techniques beyond simple transmission and reflection measurments. The figures below show some of the ones currently available, with brief descriptions.

Attenuated Total Reflection (ATR)

This technique is a videly used experimental technique in traditional FTIR spectrometry. The Hyperion microscope on the beamline has the ability to attach an ATR objective with a Germanium internal reflection element (“prism”). This technique is suitable for measuring surface properties of samples as the penetration depth of the IR light is about 1 μm. The benefit of this technique is that sample preparation is very easy, as the sample is placed in direct contact with the internal reflection element. This allows for samples to be measured that are not easily made into mulls, or KBr disks.

Grazing Incidence Reflection

Grazing Incidence Reflection is used to measure atomically thin layers on surfaces. It works when the layer thickness is less than the wavelength of the incoming radiation. GIR is suited for when other traditional sample preparation techniques are not possible. It has been used for measuring self-assembled monolayers (SAMs) on metal surfaces, and other organic molecules absorbed on the surfaces of various metal and semiconducting substrates.

IR spectroscopy with polarized light

The available Hinds Photoelastic Modulator is suited for doing measurements on samples that exhibit differential absorption between s- and p-polarized light.

Flow cell for in situ imaging of biological samples

This sample holder was designed and constructed at the Canadian Light Source. The living cell cultures are accommodated between two crystal (usually CaF₂) windows that are transparent in the Mid-IR range. Thin (~15 μm) PTFE spacers are used to define the distance between the windows. A buffer solution can be flown during the infrared measurements to keep the living cell cultures under optimal conditions.

The setup can be manufactured of different polymers or metals upon request.

Sample holders with temperature control for microscopy

Wide temperature range

An Instec HCS601 sample holder for operation between -190 °C to 600 °C, with ramping and cooling capabilities for time-resolved temperature dependent studies.

Large area optical access

A liquid sample cell has been designed that can be used with the microscope for transmission measurements that allows for highly accurate temperature control. The cell can operate from -10 °C to 100 °C, with ramping and cooling capabilities for time-resolved temperature dependent studies.