Infrared spectroscopy based on broadly tunable quantum cascade lasers and polycrystalline diamond waveguides.
Julian HaasErnesto Vargas CatalánPierre PironMikael KarlssonBoris MizaikoffPublished in: The Analyst (2018)
Recently emerging broadly tunable quantum cascade lasers (tQCL) emitting in the mid-infrared (MIR) are a versatile alternative to well established thermal emitters in combination with interferometers as applied in Fourier transform infrared (FTIR) spectroscopy. The wide and highly spectrally resolved wavelength tuning characteristics along with superior spectral energy density renders laser-based vibrational spectroscopy methods an efficient alternative vs. conventional molecular spectroscopies. Using diamond in attenuated total reflection (ATR) sensing formats benefits from the physical robustness and chemical resistivity of the internal reflective element (IRE) material. While inherent material absorption frequently limits the optical path length within diamond ATR elements, the herein presented design combining bright tQCLs with a multi-reflection polycrystalline diamond (PCD) ATR element enables an optical beam path length of approximately 5 cm. Thereby, sensitive spectroscopic measurements in the MIR are enabled. As an example, non-invasive glucose monitoring in human saliva is examined, highlighting the potential benefits of the proposed analytical concept with regards to exquisite sensitivity and selectivity in combination with a robust sensing interface, i.e., diamond. This approach paves the way towards directly analyzing molecular constituents in complex and potentially corrosive biomedical and biochemical matrices.
Keyphrases
- energy transfer
- high resolution
- single molecule
- cell proliferation
- light emitting
- long non coding rna
- dna damage response
- high speed
- endothelial cells
- molecular dynamics
- long noncoding rna
- physical activity
- quantum dots
- density functional theory
- mental health
- endoplasmic reticulum stress
- molecular dynamics simulations
- monte carlo
- optical coherence tomography
- oxidative stress
- mass spectrometry
- magnetic resonance
- induced pluripotent stem cells