Student seminar: FEIR: A new paradigm for IR detection-based diagnostics

Fourier Transform Infrared (FTIR) spectroscopy can detect the vibrational fingerprints of molecule sand has become a universal tool which finds applications in biomedical, chemistry, space and defence research. However, FTIR comes with a major limitation: the typical concentration required is 0.1M to 5M to compensate for IR transitions that have weak extinction coefficients. In this regard, achieving single molecule IR sensitivity remained a holy grail. Recently, single molecule IR sensitivity was achieved by encoding weak IR signals with fluorescence detection. In this talk, I will discuss this new method called Fluorescence Encoded IR (FEIR) spectroscopy that has increased the sensitivity of IR spectroscopy by 6 orders of magnitude, from mM to nM concentrations. I will discuss how the vibrational information can be embedded in fluorescence and how FEIR allows access to information about the superposition of vibrational states ^[1,2].The extension of FEIR technique to achieve the single molecule sensitivity ^[3]with 1 nM sample concentration will also be discussed. I will conclude my talk with a brief application of FEIR to wide field imaging that was demonstrated recently as multi-dimensional wide-field IR encoded spontaneous emission (MD-WISE) ^[4]to distinguish the chromophores having similar electronic absorption and emission spectra.