Ultrafast spectroscopy of C-H vibrations in pathogenic bacteria in 3-μm spectral range

Dynamic optical density spectra were obtained under multipulse excitation of bacterial cultures of S. aureus and P. aeruginosa by 3 μm mid-infrared ultrashort laser pulses, corresponding to the vibrational excitation of the C–H bonds of the bacterial cell. These spectra demonstrated pronounced laser intensity-dependent blue spectral shift, presumably associated with the breaking of hydrogen bonds, which are responsible for the formation of secondary and tertiary protein structures.