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Indus-1 Beamlines

Photo Physics Beamline

Introduction

Photophysics beamline is a medium resolution beamline in operation at INDUS-1 synchrotron source, useful for photoabsorption experiments in the UV-VUV region. The beamline is being used extensively for VUV spectroscopy of molecules of current interest in Atmospheric sciences, Astrophysics, Astro-chemistry, Combustion, Plasmas, Semi-conductor etching, Nuclear solvents etc.

The scopes of experiments which can be carried out using photophysics beamline include:

  • Photoabsorption studies of atoms, molecules and radicals in gas phase, condensed phase as well as matrix isolated phase down to 10K.
  •  Reflectivity and fluorescence of solid samples at room and low temperatures.
  • Photochemistry of molecules in excited states consequent of VUV photon absorption

Beamline Details

Acceptance (Angular)

41 mrad (H) x 5.6 mrad (V)

Mirror1

Toroidal mirror (Gold coated) to focus the SR beam on the  entrance slit of the  monochromator

Monochromator

1-m Seya-Namioka monochromator with gold coated spherical grating (2400 g/mm).

Mirror 2

Toroidal mirror (gold coated) to refocus the beam to a sample at a distance of one meter

Spot size

1mm(H)×1mm(V)  ( Solid samples)
 6mm(H)×8mm(V)  (for gas phase)

Photon flux

108 Photons/sec (Typical)

Wavelength Range

500 – 3500 Å (for solids);
1100 – 3500 Å (for gas phase)

Detection   

Sodium salicylate coated window with VUV to visible sensitive photomultiplier.                   


Optical Layout of the Beamline
Optical Layout of the beamline


Mechanical Layout of the Beamline

Mechanical Layout of the beamline


Experimental Facilities Available

  1. Gas phase photo-absorption spectroscopy
  2. Experimental set up for solid samples
  3. Low temperature (Matrix Isolation) spectroscopy
Gas phase absorption cell
Schematic of MIS setup
Gas phase absorption cell
Schematic of MIS setup


Photophysics beamline at Indus - 1
Photophysics beamline at Indus-1


Some Research Studies being pursued

Experimental programs on photophysics beamline include VUV spectroscopy of polyatomic molecules in gas and solid phase, study of temperature dependent optical properties of solids, evaluation of detectors required for the inverse photoemission studies, and optical properties of irradiated laser materials. A representative few scientific issues addressed in the study of electronic spectroscopy of molecules are:
  • Electronic excitations up to and beyond the first ionization potential.
  • Change in geometry and vibrational frequencies of excited states.
  • Valence/Rydberg nature of excited states and assignment of Rydberg series using quantum defect analysis
  • Assignment of vibrational progressions arising from fundamental/ combination modes accompanying the valence /Rydberg transitions including hot band contributions arising from low lying vibrational/ torsional modes.
  • Study of vibronic coupling, charge transfer excitations and Renner-Teller effects.
  • Comparative studies of excited electronic state structure in isotopically substituted, iso-electronic and substituent molecules.
  • Quantum chemical calculations for vibrational frequencies and excited state energies of molecules using GAMESS and Gaussian.

Recent Ph.D theses which include experimental work carried out on photophysics beamline (2013-14).

  1. Shri. M. Maniraj, IUC-DAE-CSR
    “Unoccupied electron states probed by inverse photoemission spectroscopy and related studies”,
    submitted to DAVV, Indore.

  2. Shri. Param Jeet Singh, AMPD, BARC
    "Synchrotron radiation based VUV spectroscopy of some polyatomic molecules of environmental interest”,
    submitted to HBNI, Mumbai.

  3. Shri. Anuvab Mandal, HBNI student, BARC
    " Electronic state spectroscopy of some environmentally important molecules using synchrotron radiation”,
    submitted to HBNI, Mumbai.

results

1.Electronic state spectroscopy of di-iodomethane (CH2I2)

The electronic absorption spectrum of diiodomethane in the 3.7-11.8 eV region is investigated. The absorption bands in the 3.7-6.2 eV region are attributed to valence transitions, while the VUV spectrum (6.2-11.8 eV) is dominated by several Rydberg series converging to the first four ionization potentials of CH2I2 corresponding to removal of an electron from the outermost non-bonding orbitals. Rydberg series are assigned based on a quantum defect analysis. TDDFT calculations of excited states support the analysis and help in interpretation of the Rydberg and valence nature of observed transitions. Vibronic features accompanying the Rydberg series are mainly due to excitation of the C-I symmetric stretch and CH2 wag modes, with smaller contributions from the C-H symmetric stretch. The unusually high underlying intensity in parts of the VUV spectrum is attributed to valence states with high oscillator strength. This is the first report of a comprehensive VUV study of CH2I2 in the 6.2-10.5 eV region. The VUV absorption spectrum of CD2I2 which serves to verify and consolidate spectral assignments is also reported for the first time. (J. Chem. Phys. 2014)

Figure: Rydberg series observed in the VUV photoabsorption spectra of CH2I2 and CD2I2
Figure: Rydberg series observed in the VUV photoabsorption spectra of CH2I2 and CD2I2

2.Study of excited states of Aniline 3.75 - 11.5eV region

The photo-absorption spectrum of aniline (C6H5NH2) in 3.7-11.2 eV is recorded at a resolution of 0.008 eV 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 structure less 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 assigned. Observed vibrational features are assigned to transitions from the ground state A' to the excited states 1A", 3A', 5A", 6A', and 10A" in C8 symmetry. Time dependent density functional theory calculations are employed to obtain the vertical excitation energies and the symmetries of the excited states in equilibrium configuration. The experimental and theoretical work carried out provides a comprehensive picture of the VUV photoabsorption spectrum of aniline up to the third ionization limit. (J. Chem. Phys. 2013)
Figure: Photo-absorption spectrum of aniline in the UV-VUV region
Figure: Photo-absorption spectrum of aniline in the UV-VUV region
Recent Upgrades
  • Beamline upgraded to improve step size resolution 0f 0.01Å, wavelength reproducibility of one step and a resolving power >2500.
  • Augmentation of low temperature facility with a FTIR spectrometer to study UV-VUV induced photochemical reaction products in molecules is in progress.

Publications

List of Journal Publications

  1. Journal of Quantitative spectroscopy and Radiative
    Trans Vol.151, 76, 2015.

  2. Journal of Quantitative Spectroscopy & Radiative
    Transfer Vol.149, Pg.291, 2014.

  3. Journal of Quantitative Spectroscopy and Radiative
    Transfer Vol.147, Pg.121, 2014.

  4. Journal of Quantitative Spectroscopy and Radiative
    Transfer Vol.144, Pg.164, 2014.

  5. The Journal of Chemical physics
    Vol.140, Pg.194312, 2014.

  6. Journal of Quantitative Spectroscopy and Radiative
    Transfer, Vol. 129, Pg.204, 2013.

  7. Asian Journal of Physics
    Vol. 22, Pg.19, 2013.

  8. Journal of Chemical Physics,
    Vol.139, Pg.064303-1, 2013.

  9. Journal of Quantitative Spectroscopy and Radiative
    Transfer, Vol.114, Pg. 2, 2013.

  10. Review of Scientific Instruments
    Vol.83, Pg 046107:1, 2012.

  11. Journal of Quantitative Spectroscopy and Radiative
    Transfer Vol.113, Pg.1553, 2012.

  12. Asian Journal of Spectroscopy
    Special issue 2012, Pg. 121, 2012.

  13. Asian Journal of Spectroscopy,
    Special issue, Pg. 107, 2012.

  14. Journal of Quantitative Spectroscopy and Radiative
    Transfer Vol.113, Pg.58, 2012.

  15. Spectroscopy letters, an International Journal for Rapid Communication
    Vol.45, Pg.65, 2012. 

  16. Review of scientific Instruments
    Vol.82, Pg. 093901:1, 2011.

  17. Spectroscopy letters, an International Journal for Rapid Communication,
    Vol.43, Pg.290, 2010.

  18. Spectroscopy letters, an International Journal for Rapid Communication,
    VOL.42, Pg.1, 2009.

  19. Applied Surface science,
    Vol. 253, Pg. 4515, 2007.

  20. J. Phys. D: Appl. Phys. Vol.39, Pg.4059, 2006.

  21. Rapid communications in mass spectrometry,
    Vol.19, Pg. 1522, 2005.

  22. Journal of optics (India),
    Vol.32, Pg.169, 2003.

  23. Nuclear Instrumentation Methods in Physics Research A,
    Vol.467, Pg.613, 2001.

  24. Journal of Optics (India),
    Vol.28, Pg. 145, 1999.

  25. Sadhana Journal, India,
    Vol. 22, Pg. 1, 1997.

BARC REPORTS

  1. Photoabsorption studies of polyatomic molecules using Indus-1 synchrotron radiation source,
    BARC Report – BARC/2004/E/011.

  2. A laboratory experimental setup for the reflectivity experiments,
    BARC Report No – BARC/2000/E/032.

  3. An ultrahigh vacuum monochromator for photophysics beamline,
    BARC Report No. – BARC/2000/E/020.

  4. Optimisation of the Optical lay-out for the photophysics beamline at INDUS-1 synchrotron radiation source,
    BARC Report - BARC/1998/E/011.

  5. Image evaluation of one meter Seya-Namioka monochromator at INDUS-1 synchrotron radiation source,
    BARC Report No - BARC/1994/E/044.

PRESENTATIONS IN INTERNATIONAL/ NATIONAL CONFERENCES

  1. Study of Rydberg States of Di-iodomethane Using VUV Synchrotron Radiation.
    Presented at Trombay Symposium on Radiation Photochemistry,
    BARC, Mumbai, Jan 6-9, 2014.

  2. Synchrotron based VUV spectroscopy in gas and matrix isolated phase.
    Presented at 7th Oceania forum for synchrotron radiation research,
    Egret Himeji, Hyogo, Japan, September 21 -24, 2013.
  1. Electronic structure of dibromomethane: VUV spectroscopy with synchrotron radiation source and TDDFT calculations.
    Presented at Current Trends in Theoretical Chemistry,
    BARC, Mumbai, September, 26-28, 2013.

  2. VUV Spectroscopy of Environmentally Important Molecules in Gas Phase and Matrix isolated Phase Using Synchrotron Radiation.
    Presented at National Symposium on Radiation and Photochemistry (NSRP· 2013),
    Department of Chemistry, North Eastern Hill University (NEHU), Shillong Meghalaya, March 20 - 22, 2013.

  3. VUV spectroscopy of SO2 isolated in Argon matrix using synchrotron radiation.
    DAE-BRNS Symposium on Atomic, Molecular and Optical Science
    held at IISER, Kolkata, AMOS, December 14-17 2012.

  4. Probing vibronic structure of highly excited states of polyatomic molecules using synchrotron radiation.
    Presented at 10th Asian International Seminar on Atomic and Molecular Physics 2012,
    National Dong-Hwa University, Taipei, Taiwan, October 23-30, 2012.

  5. Vacuum Ultraviolet Absorption Spectra of Alkyl Phosphates.
    Presented at International Conference on Molecular Spectroscopy of Advanced materials and Biomolecules-IMSAB-2012,
    Bishop Moore’s College, Mavelikkara, Kerala, 7-9 August, 2012.

  6. The role of torsional vibrations in the electronic absorption spectrum of acetone.
    Presented at 99th Indian Science Congress,
    KIIT University, Bhubaneswar, Jan 3-7, 2012.

  7. VUV Photoabsorption Studies of CHCl3 and CDCl3 Using photophysics Beamline at Indus-1.
    Presented at National symposium on radiation & Photochemistry,
    JNV, Jodhpur, March 10-12, 2011.

  8. Study of perturbations in electronic states because of charge Trans. mechanisms in electronic absorption spectrum of aniline.
    Presented at DAE-BRNS symposium on Atomic, Molecular and Optical Physics (SAMOP-2011),
    Department of Physics, Karnatak University, Dharwad, February 22-25, 2011.

  9. Effect of Isotopic Substitution on Valence and Rydberg Transitions Observed in the Electronic Spectrum of Acetone.
    Presented at DAE-BRNS SYMPOSIUM on Atomic, Molecular and Optical Physics (SAMOP-2011),
    Department of Physics, Karnatak University, Dharwad, February 22-25, 2011.

  10. A microcontroller based movement control and data acquisition system for the Photophysics spectroscopy beamline at INDUS I Synchrotron Radiation Source. National Conference on Emerging Technologies in Electronics, Mechanical and Computer Engineering,
    Indore Institute of Science and Technology, Indore, April 17–18, 2010.

  11. PHOTOPHYSICS BEAMLINE AT INDUS-1
    Presented Topical conference on EM interaction with atoms, molecules, and clusters” (TC-2010)
    held at RRCAT, Indore, March 3 – 6, 2010.

  12. VUV Photoabsorption Studies of Nitrous Oxide Using Synchrotron Radiation.
    Presented Topical conference on EM interaction with atoms, molecules, and clusters” (TC-2010)
    held at RRCAT, Indore, March 3 – 6, 2010.

  13. Photo absorption spectra of Formaldehyde in the 3-11 eV region using synchrotron radiation.
    Presented Topical conference on EM interaction with atoms, molecules, and clusters” (TC-2010)
    held at RRCAT, Indore, March 3 – 6, 2010.

  14. Photoabsorption studies on mixtures of CH2F2 with atmospheric gases.
    Presented at National conference on Atomic, molecular and nuclear physics,
    MMH College, Ghaziabad, Pg.69, November 5-7, 2009

  15. Photoabsorption spectra of carbonyl sulfide using synchrotron radiation.
    Presented at National conference on Atomic, molecular and nuclear physics,
    MMH College, Ghaziabad, Pg.29, November 5-7, 2009

  16. VUV Photoabsorption Studies of Difluoromethane (CH2F2) Using Synchrotron Radiation.
    Presented at DAE-BRNS Symposium on Atomic, Molecular and Optical Physics,
    Inter University Accelerator Centre, New Delhi, Feb. 10 -13 2009.

  17. Photo-absorption Spectra of Ammonia.
    Presented at DAE-BRNS Symposium on Atomic, Molecular and Optical Physics,
    Inter University Accelerator Centre, New Delhi, Feb. 10 -13 2009.

  18. Photoabsorption spectra of Carbon disulphide using Photo Physics Beamline at Indus-1 SR Source.
    Presented at DAE-BRNS Symposium on Atomic, Molecular and Optical Physics,
    Inter University Accelerator Centre, New Delhi, Feb. 10 -13 2009.

  19. Group delay dispersion induced spectral interference phenomena in optical thin film light scattering using synchrotron radiation.
    presented at Photonics 2006.

  20. A TOFMS and VUV absorption study on Dimethyl disulfide (DMDS) and Dimethyl sulphoxide (BMSO) using photophysics beamline at Indus-1.
    Presented at National Symposium on Radiation and Photochemistry, NSRP-2005,
    Department of Physics, Karnataka University, Dharwad, Karnataka, India, during 17-19, January 2005.

  21. Studies on methyl Iodide using photophysics beamline at Indus-1.
    Presented at 15th National conference on Atomic and molecular Physics,
    NCAMP-XV, held at Physical Research laboratory, Ahmadabad, December 20 –23, 2004.

  22. Photoabsorption studies of polyatomic molecules using the photophysics beamline at Indus-1.
    Presented at 15th national conference on Atomic and molecular Physics,
    NCAMP-XV, Physical Research laboratory, Ahmadabad, December 20 –23, 2004.

  23. Preliminary results on VUV reflectivity experiments.
    Proceedings, DAE-BRNS workshop on thin film multilayers,
    BARC, Mumbai, 6 - 8, October, 1999.

  24. Studies on fragmentation dynamics of Cholroflurohydrocarbons using photoelectron and photoion coincidence (PEPICO) and photo-electron and photoion coincidence (PEPICO) techniques.
    Presented at India-Italy workshop on utilization of Synchrotron Radiation from Elettra,
    Saha Institute of Nuclear Physics, Calcutta, November 10-13, 1998.

  25. A one meter VUV monochromator for the photophysics beamline at INDUS-1.
    Presented   at International Conference on Spectroscopy: Perspectives & Frontiers,
    BARC, Mumbai, January 3-5, 1996.

  26. Spectroscopic beamlines at INDUS-1 Synchrotron Radiation Source facility.
    Proceedings, Fourth International Conference on Synchrotron Radiation Sources and the Second Asian Forum on Synchrotron Radiation,
    Hyundai Hotel, Kyongju, Korea, Oct. 25-27, 1995.

  27. Design and evaluation of beamlines on INDUS-1 synchrotron source.
    Proceedings, International Conference on Synchrotron Radiation Sources,
    CAT, Indore, Feb. 3-6, 1992, Pg.354.

  28. Design and development of photophysics beamline.
    Proceedings, International Conference on Synchrotron Radiation Sources,
    CAT, Indore, Feb. 3-6, 1992, Pg.373.

  29. Design and development of beamlines at INDUS-1.
    Presented at 46th Okazaki international Conference on application of synchrotron radiation to molecular science, present status and future prospects,
    Okazaki, Japan, Dec. 16-18, 1992.

Contacts


Dr. M. N. Deo
Head, Atomic and Molecular Physics Division (A.M.P.D)
BARC, Trombay, Mumbai-400 085
Email: mndeo(at)barc.gov.in


Dr. B.N. Rajasekhar
A.M.P.D, BARC at RRCAT
Indore – 452 013.
Tel: +91 731 248 8141
Email: bnrs(at)rrcat.gov.in


Dr. (Smt.) Aparna Shastri
A.M.P.D, BARC, Trombay,
Mumbai - 400 085.
Tel: +91 22 2559 0343
Email: ashastri(at)barc.gov.in
Dr. (Smt.) Sunanda K.
A.M.P.D, BARC, Trombay,
Mumbai - 400 085.
Tel: +91 22 2559 0351
Email: sunanda(at)barc.gov.in
Mr. Param Jeet Singh
A.M.P.D, BARC, Trombay,
Mumbai - 400 085.
Tel: +91 22 2559 2995
Email: singhp(at)barc.gov.in


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