Soft x-ray microscopy for molecular imaging in a biological cell

One of the distinct characteristics of soft X-ray microscopy is ability to image elements and molecules using the profiles of absorption spectra for constituent elements. The absorption peak specific to a chemical bond appears in XANES (X-ray Absorption Near Edge Structure) and makes molecular mapping possible. Molecules containing light elements such as Ca, P and S are favorable targets for soft X-ray microscopy. The present paper describes a brief overview of soft X-ray microscopy and its application to molecular imaging in a biological cell, absorption spectra of biological molecules such as DNA, protein, nucleotides and amino acids, and our trial for element mapping in a biological cell with soft X-ray contact microscopy. (author)