The UV 1 beamline at ASTRID
ISA's ultra violet beamline, UV1, has been designed to cover the low photon energy region from about 700 to 100 nm using two gratings. The monochromator has been designed to provide a high flux with a moderate resolution (R > 1000) and to preserve the high degree of linear polarisation of the source synchrotron radiation. The use of UV1 is divided into two categories: UV photoabsorption spectroscopy and Circular Dichroism (CD).
The technical details of the beamline can be found on the UV1 optical specification page.
UV photoabsorption spectroscopy is being carried out on both gas samples and solids. So far the absolute UV photoabsorption cross section of more than 60 molecules has been measured at UV1. Many of these molecules are of atmospheric, plasma etching or biological interest. Photoabsorption spectroscopy of solids is being carried out on both ices formed by deposition of gases on a cold UV-transparent substrate, and on solid thin films.
The photoabsorption spectroscopy on ices experiment mounted on the UV1 beamline.
Synchrotron Radiation Circular Dichroism.
The wavelength range of the high energy grating (100 to 350 nm) is a biologically important wavelength region, and the high degree of linear polarisation of the radiation from UV1 in makes the beamline well suited for Synchrotron Radiation Circular Dichroism (SRCD) spectroscopy of optically active macromolecules.
Circular Dichroism (CD) spectroscopy measures the difference in absorption between left and right handed circularly polarized light in chiral molecules. It is an established biophysical method probing the secondary structure (e.g. helices, beta-sheets, turns etc.) of peptides, proteins and nucleic acids which have distinct CD bands in the far-UV and VUV.
|The principle behind CD spectroscopy. The light from UV1 is passed into a Photo Elastic Modulator (PEM) which converts the linearly polarized light into alternating left and right handed polarized light. The two polarizations are differently absorbed, and the difference in absorption is detected with a Photo Multiplier Tube (PMT)|
More details of the SRCD facility at ASTRID can be found in the SRCD folder.
Due to high user demand for beam time on UV1 a new beamline optimized for SRCD spectroscopy, CD1, has recently been built.
For further information on and access to the UV1 beamline please contact:
Last Modified 13 June 2009