Photothermal Spectroscopy Corp (PSC) is a Santa Barbara, CA, based scientific equipment company that pioneered sub-micron IR microscopy and spectroscopy. PSC’s vision is to enable the power of sub-micron IR spectroscopy to be applied to high value problems in both industry and academia via the adoption of O-PTIR and co-located multi-modal techniques.
O-PTIR is one of the highest growth IR microscopy techniques and addresses application areas in life science, microplastics, bioplastics, semiconductor, failure analysis and chemical and polymeric materials.
mIRage® IR Microscope
With the introduction of the mIRage® IR microscopy, we pioneered a breakthrough sub-micron-Infrared spectroscopy and microscopy technique called Optical Photothermal Infrared (O-PTIR). O-PTIR eliminates key limitations of traditional IR spectroscopy providing sub-micron IR spatial resolution with transmission-like FTIR quality spectra in non-contact reflection mode with no Mie scattering effects.
The subsequent release of the mIRage-R combined O-PTIR with Raman technologies introducing the world’s first simultaneous sub-micron IR Infrared and Raman microscope and spectroscopy system, providing simultaneous IR and Raman data from the exact same spot, at the same time, with the same sub-micron spatial resolution enabling complementary and confirmatory data from both techniques.
The launch of the mIRage-LS extended platform capabilities by combining O-PTIR with co-located fluorescence microscopy and further improved IR spatial resolution to sub-500nm. The mIRage-LS allows O-PTIR technology to address high value life science research problems not able to be addressed by conventional IR microscopy.
Optical Photothermal IR Spectroscopy
Optical Photothermal infrared spectroscopy (O-PTIR) used on the mIRage IR microscope is a result of over a decade of expertise in photothermal physics after the initial development of AFM-based nanoscale IR spectroscopy.
O-PTIR: How it works
O-PTIR overcomes the IR diffraction limit by combining a mid-IR pulsed, tunable laser that heats the sample. When the IR laser is at a wavelength that excites a molecular vibration in the sample, absorption occurs, thereby creating photothermal effects including photothermal expansion. A visible probe laser, focused to 0.5 µm spot size, measures the photothermal response via the scattered light, as shown in the illustration above.
The component of the reflected visible laser signal that is modulated at the IR pump laser repetition rate is directly proportional to the absorption coefficient of the sample at that wavenumber. The IR pump laser can be tuned through the entire fingerprint region in one second or less, to obtain an IR spectrum.
By operating in reflection mode, O-PTIR eliminates several longstanding limitations and has substantial benefits for the IR community, including sub-micron resolution using a non-contact optical method. The sub-micron resolution is demonstrated (right), showing reflection mode spectra on a multi-layer packaging film measured 0.5 µm apart with highly differentiated chemical fingerprints indicating different materials.
Measurements are collected quickly and easily without need for sample contact, unlike ATR spectroscopy. Additionally, O-PTIR provides spectra comparable to FTIR without the dispersive artifacts observed in ATR. By operating in reflection mode, the need for thin samples is also eliminated, leading to dramatically easier sample preparation and faster turnaround times.