Nanoscale needle shaped histidine and narrow vibrational Raman bands using visible excitation

We observe intense and narrow vibrational Raman bands of nanoscale needles shaped histidine. The nano-needles have been grown from droplets of aqueous histidine (30 mM) on silica. Scanning electron microscopy reveals a combined structure of folded flat leaves and needles with diameters in the 50 nm range. The observed spectral bands are compared with density functional calculations. The C–H stretching vibrational bands of the imidazole ring are identified. C–H stretching mode of the back bone is found to be strongly conformational dependent.