Development of a 6.65 m off- plane eagle spectrometer for a high resolution vacuum ultraviolet beam-line at Indus-I synchrotron radiation source

6.65 m vacuum ultraviolet (VUV) spectrometer has been designed and fabricated indigenously using concave grating (concave radius = 6.65 m) of frequency 4800 grooves/mm for carrying out spectroscopic research of atomic and molecular gases and vapours using synchrotron as a source of radiation. The wavelength range of the spectrometer is 700-2000 A. The reciprocal linear dispersion of the instrument is about 0.3 A/mm. The experimentally estimated value of the wavelength resolution is 0.01 A. The spectrometer has been tested by recording spectral lines of wavelengths 1228.79A (nitrogen), 1243.18A (nitrogen), 1261.55A (carbon), 1288.42A (nitrogen), 1930.9A (carbon) under a vacuum of 10-5 torr by exciting residual gas molecules in a rotary pump evacuated discharge tube. (author)