Terahertz time-domain spectroscopy of sulfur-containing biomolecules

Abstract

We present frequency-dependent absorption coefficients and refractive indices of sulfur-containing biomolecules in the far-infrared region measured by terahertz (THz) time-domain spectroscopy (TDS). The THz radiation was generated by a surface photocurrent method with a (100)InAs wafer as a THz emitter, and its intensity was enhanced by applying a magnetic field of 1.6 T. The THz radiation was detected by the electrooptic sampling method with a ZnTe crystal. The characterization of the apparatus of THz TDS is discussed in detail. The spectral features in the THz region are different among sulfur-containing biomolecules of L,Lcystine, L-cysteine, L-methionine, and oxidized glutathione in powder. These results demonstrate that THz TDS is a promising method for studies on the low-frequency spectra of complex molecules and identification of materials. We present a calculation method to analyze the THz spectra based on a model function for dynamics of the dipoles, which allows us to obtain spectral information characterizing the low-frequency responses of the molecules. The experimental results are compared with ab initio calculations to discuss assignment of the vibrational modes.

Terahertz spectroscopy of polar solute molecules in non-polar solvents

“…The detail of the experimental set up of THz-TDS was already described elsewhere [5,6]. Briefly, femtosecond pulses from a Ti:sapphire oscillator were used for generation and detection of the THz radiation.…”

Quantitative Analysis of Amino Acids in Dietary Supplements Using Terahertz Time-domain Spectroscopy

“…Therefore, it becomes possible to achieve the selective detection of certain molecules in mixed samples, which form strong inter-and intramolecular modes in a sample mixed with impurities. Moreover, THz waves cause almost no damage to materials, and so they can be used to detect fragile biological samples [4][5][6][7][8][9] and to characterize pharmaceutical materials. [10][11][12][13] Thus, THz techniques are attracting increasing interest not only in basic research, but also for practical applications in a variety of fields.…”

Terahertz Time-domain Spectra of Aromatic Carboxylic Acids Incorporated in Nano-sized Pores of Mesoporous Silicate

“…The THz-TD absorption spectra of DNA 10 and amino acids [11][12][13][14] have revealed that specific resonance patterns can be identified as the vibrational modes of intermolecular hydrogen bond networks. Recently, we found that incorporating target molecules in nanosized spaces is effective in reducing the influence of the intermolecular modes of the target molecule.…”