O-PTIR: Photothermal mIRage LS Optical Photothermal Infrared Microscope
Overview
Optical Photothermal Infrared Spectroscopy (O-PTIR) overcomes the optical diffraction limit of light by using both a mid-infrared pump laser and a visible probe laser. The technique relies on the photothermal effect, where absorbed infrared radiation is converted into heat, causing localized thermal expansion of the sample. When photons are absorbed by a material, their energy excites molecular vibrational modes and relaxes through re-emitting light (ie. Raman), or non-radiative decay (photothermal effect) which generates heat. This localized heating produces a small but measurable thermal expansion and refractive index change in the material. O-PTIR measures this change using a focused visible laser (532nm or 785 nm) enabling spatial resolution ~500 nm.
The mIRage LS microscope is capable of measuring correlative fluorescence, Raman and OPTIR. The default OPTIR configuration is “co-propagation” where the probe and IR lasers are sent through a reflective Cassegrain objective that uses mirrors to direct the IR light and classic lenses for guiding the visible probe laser
Spectral Range:
IR
- QCL laser ~ 2cm-1 resolution
977-1803 cm-1 Fingerprint, 1997-2331 cm-1 Silent Region Chip, 2667-3001 cm-1 CH - M2 OPO laser ~4cm-1 resolution
2711-3603 cm-1
RAMAN
- 532nm and 785 nm lasers with dual gratings
Features of the MIRage LS:
- OPTIR with co-propagation or counter-propagation configurations -
Co-propagation: Ideal for reflective samples, screening and thick samples. Samples can be mounted on a variety of substrates.
Counter propagation: Ideal for higher spatial resolution, thin, transparent samples, cell imaging, etc. Samples are mounted on CaF2 windows. - Widefield Fluorescence or Autofluorescence Imaging
- Simultaneous IR & Raman Spectroscopy and Imaging
- Temperature Stage measurements (-40°C to 120°C)
- Infrared Measurements for O-H, N-H, and C-H bonds with the extended spectral range from 2711-3603 cm-1
Getting Started and Training Information
The mIRage OPTIR is located in Deep Lab, SPM Room B111
In order to become a qualified user on the Photothermal mIRage OPTIR, please follow each of these steps in the order listed below:
- Complete the process to become a lab member of nano@stanford and follow the instructions to activate a NEMO account.
The safety training listed under “Spilker, Shriram, McCullough, Moore, Deep Lab” must be completed. - Complete the On-the-job Laser Safety & Access for Deep Lab.
- Complete the OPTIR New User Intake Form.
- Join the mailing list optir-users
- Read the mIRage LS Standard Operating Procedure (SOP).
Email nano-ramanstaff@lists.stanford.edu to schedule a 2 hour qualification session. Please provide your schedule availability to expedite the scheduling process.