The photoabsorption spectrum of aniline (C6H5NH2) in gas phase in the 30,000-90,000 cm(-1) (3.7-11.2 eV) region is recorded at resolution limit of 0.008 eV using synchrotron radiation source for the first time to comprehend the nature of the excited valence and Rydberg states. The first half of the energy interval constitutes the richly structured valence transitions from the ground to excited states up to the first ionization potential (IP) at 8.02 eV. The spectrum in the second half consists of vibrational features up to second IP (9.12 eV) and structureless broad continuum up to the third IP (10.78 eV). The electronic states are assigned mainly to the singlets belonging to π → π* transitions. A few weak initial members of Rydberg states arising from π → 4s, np or nd transitions are also identified. Observed vibrational features are assigned to transitions from the ground state A' to the excited states 1A", 3A', 5A", 6A', and 10A" in C(s) symmetry. Time dependent density functional theory (TDDFT) calculations at B3LYP level of theory are employed to obtain the vertical excitation energies and the symmetries of the excited states in equilibrium configuration. The computed values of the transition energies agree fairly well with the experimental data. Further the calculated oscillator strengths are used to substantiate the assignments of the bands. The work provides a comprehensive picture of the vacuum ultraviolet photoabsorption spectrum of aniline up to its third ionization limit.

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An indjgellOus deS;g/l, fabricatjOlI and perfonnance evaluation 0/ a vacuum ultraviolet (VUV) spectrometer are described/or carrying out spectroscopic research 0/ atomic OIld moleeular gases and vapours using fndus-} synchrotron source 0/ radiation commissioned al Centfr Jor Advanced Technofogy, fndore Indio. The spectromeler is based on an off-fJXis Eagle type 0/ compact mountillg suitable tor the VUV region of the spectrum. The speclrometer consists of a concave grating 0/ radius 0/ curvaJure 6.65 m as a dispersing element and a photomultiplier tube (PMT) as a radiation detection element. The reciprocallinear dispersion of the instl'Ument is ahout J .24 Älmm wirh a gratin! 0/1200 grooveshm/L The wavelength resolution achieved is 0.08 Ä. Thc wavelength resolution eml be obUJined os 0.005 A by repku:ulg the presem grating 0/ J 200 grooves//Il1II with a grating 0/4800 grooves!mm use/ul itl the wavelength region/rom 400 Ä 102000 Ä. The present wavelength range o/the spectroineter is/rom 400 Ä to 58O(J Ä with the grating 0/1200 grooveshmn. For one wavelength setring 0/ the grating, 0 spectral band 0/200 A can he recorded by moving the PMT along the Rowftmd circle 0/ diameter 6.65nL For c1umgiflg the wavelength region, the grating ls first rota ted and then transfated by /WO stepper 111Otors controlled by apersonal compUU!r. The accuracy achieved in the angular rotation 0/ the grating is 1 are-sec whereas the accuracy achieved ;/1 the linear displacemem 0/ the grating is 22 microns. The precisiol/ opricol alignmem Jor obtaining a weil /oclIsed spectrlun and subsequelll per/onnance evaluation 0/ (he spectromeJer have been dolle in the wavelength regiol//rom 2900 A to 5800 Ä because 0/ ,he availability 0/ speclrallmflps sl/ch as mercllry discharge lamp and He-Ne faser and due '0 the cOllveniellce 0/ aligllillg the oplicol spectromerer ill air rather than in vacuum. VariollS specmlf fines 0/ mercury have been recorded in Ihe phOlographie mode os weil as in rhe photoeleclric mode. The recorded specrral lilles o/wavelengths 5790.662967.28 Ä ore /ound 10 be sharp. The spectrometer will' be coupled 10 lhe high resolution VUV beam line otllldu,s-1, Cemrefor Advance Techl/ology, Indore_ The expected resolution will be 0.005 Ä in the wovefengrh range 0/700 Ä to 2000 A by wing lhe grating 0/4800 grooveNmm as a dispersillg element.

A refocusing modified velocity map imaging electron/ion spectrometer adapted to synchrotron radiation studies Rev. Sci. Instrum. 76, 053302 (2005); 10.1063/1.1900646 Erratum: The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of absorption bands of NO [J.The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of: II. The δ(1,0) band of NOAbstract. An indigenously developed high-resolution vacuum ultraviolet (VUV) spectrometer has recently been commissioned at the INDUS-1 Synchrotron Source, Indore, India for carrying out spectroscopic research of atomic and molecular gases. The spectrometer uses a 6.65-meter concave grating in off-plane Eagle mounting and a photomultiplier tube (PMT) for recording the intensity profile of various spectral lines. Experimental performance of the spectrometer has been tested using laboratory sources and 1200 grooves/mm and 4800 grooves/mm concave gratings. Wavelength resolutions of 0.08 Å and 0.01 Å have been achieved when 1200 grooves/mm and 4800 grooves/mm concave gratings have been mounted successfully in the spectrometer. The instrument has been integrated with the high resolution VUV beamline at INDUS-1 and its performance is being evaluated with synchrotron radiation.

The F. T. Spectrum of CS molecule was recorded with Bruker IFS 120 HR spectrometer at a spectral resolution of 0.03 cm −1 using liquid nitrogen cooled InSb detector in the region 10500 -1800 cm −1 . Intense spectrum of CS radical was excited by DC discharge of mixture of CS 2 (120 mTorr) and He (2 Torr) in flowing condition. Two hours integration time was used for obtaining a good S/N ratio. For the first time seven bands of a' 3 Σ -a 3 Π transition of CS molecule are observed lying between 8000 -4800 cm −1 region. Rotational analysis of these bands, viz. 7-1, 6-1, 5-0, 4-0, 3-0, 2-0, and 3-1 will be presented.