# SGM

BACK

Overview of the SGM beamline.

# OVERVIEW

The SGM beamline is dedicated to the spectroscopy in the soft x-rays (250 to 1200 eV) energy range. It focus on the electron spectroscopy of surfaces and absorption spectroscopy of low atomic number elements and first row transition metals with applications to atomic and molecular physics, surface science, materials science and condensed matter physics.

The SGM is a 1.67T dipole beamline providing users with monochromatic tunable photon beam in the soft X-ray range with mild resolving power and sub-milimetric spot size. Different techniques can be employed at the SGM using the endstations available at the LNLS, including X-ray Absorption Spectroscopy (XANES), X-ray scattering and reflectivity, and Photoelectron Spectroscopy (XPS).

The soft x-rays produced at SGM are valued for the unique chemical state sensitivity to light elements such as carbon, oxygen and nitrogen highly important as constituents of life and involved in many technological applications from agriculture and environment to health and nanotechnology. The soft X-rays can also probe the absorption edges of first row transition metal and rare-earth lanthanides important for correlated electron materials, catalysis and energy storage. Moreover, in electron spectroscopy such as XPS, soft X-rays sources are valuable to generate low kinetic energy electrons with very high surface sensitivity up to few atomic layers.

# EXPERIMENTAL TECHNIQUES

The following experimental techniques and setups are available to users in this beamline. To learn more about the techniques’ limitations and requirements (sample, environment, etc.) contact the beamline coordinator before submitting your proposal.

X-RAY ABSORPTION SPECTROSCOPY (XANES)

XANES is a widely used technique to determine the local geometric and/or electronic structure around the absorbing element in different materials. The energy renge in the SGM beamline is particularly suitable to investigate low Z elements and first row transition metals.

Setup: XANES endstation

The endstation is designed for X-ray absorption experiments with the samples in high vacuum at pressures below $10^{-7}$ mbar. It has different sample holders to accommodate multiple samples with different geometries. The absorption spectrum can be measured in Total Flourescence Yield mode using a photodiode (TFY) or in Total Electron Yield collecting the drain current from ground to sample (TEY). In both cases the small currents are recorded with a high sensitivity electrometer as function of the incident photon energy. The incident photon flux is monitored by current measurements in a gold mesh with approximately 80% transmission positioned before the sample.

Recent publications using this setup:

BETANCOURT, A. M.; COUTINHO, L. H.; BERNINI, R. B.; MOURA, C. E. V.; ROCHA, A. B.; SOUZA, G. G. B. DE (E) VUV and soft x-ray ionization of a plant volatile: Vanillin (C8H8O3). Journal of Chemical Physics, v. 144, n. 11, p. 114305, 2016.

MONFREDINI, T.; FANTUZZI, F.; NASCIMENTO, M. A. C.; WOLFF, W.; BOECHAT-ROBERTY, H. M. (E) SINGLE AND DOUBLE PHOTOIONIZATION AND PHOTODISSOCIATION OF TOLUENE BY SOFT X-RAYS IN A CIRCUMSTELLAR ENVIRONMENT. Astrophysical Journal, v. 821, n. 1, p. 4, 2016.

BETANCOURT, A. M.; BAVA, Y.B.; ERBEN, M. F.; CAVASSO-FILHO, R. L.; TONG, S. R.; GE, M.; VÉDOVA, C. O. D.; ROMANO, R. M. (E) Electronic properties and photofragmentation mechanisms of pyrosulfuryl chloride, ClSO2OSO2Cl. Journal of Photochemistry and Photobiology A, v. 324, p. 184-191, 2016.

NASCIMENTO, G. M. DO; PRADIE, N. A. (E) Deprotonation, Raman dispersion and thermal behavior of polyaniline-montmorillonite nanocomposites. Synthetic Metals, v. 217, p. 109-116, 2016.

BAVA, Y.B.; MARTINEZ, Y. B.; BETANCOURT, A. M.; ERBEN, M. F.; CAVASSO-FILHO, R. L.; DELLA VÉDOVA, C. O.; ROMANO, R. M. (E) Ionic fragmentation mechanisms of 2,2,2-trifluoroethanol following excitation with synchrotron radiation. ChemPhysChem, v. 16, n. 2, p. 322-330, 2015.

X-RAY PHOTOELECTRON SPECTROSCOPY (XPS)

XPS is a surface-sensitive quantitative spectroscopic technique that measures the elemental composition, chemical and electronic state of the elements within the surface of a material.

Setup: XPS endstation

The XPS endstation operates with the analysis chamber in ultra high vacuum with pressures around $10^{-8}$ mbar. It is equipped with a high resolution electron analyzer (SPECS/PHIOBOS 300) capable of resolutions up to 0.3 eV to 20 eV of energy pass. The analysis chamber has also a sputter gun for sample cleaning, a mass spectrometer and an electron gun for charging compensation. The endstation has a pre-chember with a load lock for fast sample loading and also a lamp oven for sample treatments at temperatures up to 500°C under different gases introduced with a needle valve.

Recent publications using this setup:

MORAES, T. S.; RABELO NETO, R. C.; RIBEIRO, M. C.; MATTOS, L. V.; KOURTELESIS, M.; LADAS, S.; VERYKIOS, X.; NORONHA, F. B. (E) Ethanol conversion at low temperature over CeO2-Supported Ni-based catalysts. Effect of Pt addition to Ni catalyst. Applied Catalysis B, v. 181, p. 754-768, 2016.

ALVES, L. M. S.; BENAION, S. S.; ROMANELLI, C. M.; DOS SANTOS, C. A. M.; DA LUZ, M. S.; DE LIMA, B. S.; OLIVEIRA, F. S.; MACHADO, A. J. S.; GUEDES, E. B.; ABBATE, M.; MOSSANEK, R. J. O. (E) Electrical Resistivity in Non-stoichiometric MoO2. Brazilian Journal of Physics, v. 45, n. 2, p. 234-237, 2015.

KESSLER, F.; STEFFENS, D.; LANDO, G. A.; PRANKE, P.; WEIBEL, D. E. (E) Wettability and cell spreading enhancement in poly(sulfone) and polyurethane surfaces by UV-assisted treatment for tissue engineering purposes. Tissue Engineering and Regenerative Medicine, v. 11, n. 1, p. 23-31, 2014.

AZCARATE, J. C.; ADDATO, M. A. F.; RUBERT, A. A.; CORTHEY, G.; MORENO, G. S. K.; BENITEZ, G.; ZELAYA, E.; SALVAREZZA, R. C.; FONTICELLI, M. H. (E) Surface chemistry of Thiomalic acid adsorption on planar gold and gold nanoparticles. Langmuir, v. 30, n. 7, p. 1820-1826, 2014.

X-RAY SCATTERING (XRS) AND REFLECTIVITY (XRR)

XRS with soft X-rays probes the variations in electron density near surface of materials. XRR is a special case, where one measures the electronic density variations in the direction perpendicular to the scattering plane. It is an analytical technique used in chemistry, physics, and materials science to characterize the surface of samples, particularly the interfaces of multilayered thin films.

Setup: Soft X-ray Scattering Endstation (SXRS)

The SXRS endstation is equipped with a two circle in vacuum diffractometer with motorized $latex \theta$, 2$latex \theta$ (–16 to 89 degree), $latex \chi$ and $latex \phi$. It also has an X-Y (range) stage that rotates together with the sample. The chamber operates in UHV at a pressure around $latex 10^{-8}$ mbar. The sample temperatures can be lowered down to 10K using closed circuit a He-cryostat. Additionally, a magnetic field (-17, 0, +17 kOe) can be applied parallel to the sample surface for XRR experiments. A photodiode is used for XRR measurements, while general XRS uses an in vacuum CCD.

Recent publications using this setup:

DE PAULI, M.; SANTOS, P. L.; COSTA, B. B. A,; MAGALHÃES-PANIAGO, R.; CURY. L. A.; MALACHIAS, A. (E) Understanding molecular interactions in light-emitting polymer bilayers: the role of solvents and molecular structure on the interface quality. Applied Physics Letters, v. 104, n. 16, p. 163301, 2014.

# LAYOUT & OPTICAL ELEMENTS

ElementTypePosition [m]Description
SOURCEBending Magnet0.0Bending Magnet D08 exit A (4°), 1.67 T
M1Spherical Horizontal Focusing Mirror2.8Au coated, R=94m, $\theta$=41mrad, side bounce
M2Spherical Vertical Focusing Mirror3.6Au coated, R=69.4m, $\theta$=49mrad, bounce down
SEEntrance slit6.8horizontal: 45 mm, vertical : 5 – 1000 $\mu \rm m$
GRSpherical Grating Monochromator8.8Pt coated, R=57 m, Included angle: 174° 746/1492 l/mm, bounce up
SXExit slit12.8movable horizontal: 90 mm, vertical : 5 – 1000 $\mu \rm m$
M3Toroidal focusing Mirror14.8Au coated, $\theta$=24.4mrad, Rm=52 m, Rs=0.043 m, bounce up

# PARAMETERS

ParameterValueCondition
Energy range [eV]250-500746 grating
Energy range [eV]500-12001492 grating
Energy resolution [$\Delta$E/E]$1 \times 10^{-3}$at 500 eV, 100 $\mu \rm m$ slit
Beam size at sample [$\mu \rm m^2$, FWHM]330 x 760at 500 eV
Beam divergence at sample [$\mu \rm rad^2$, FWHM]3 x 18at 500 eV
Flux density at sample [ph/s/$\rm mm^2$]$2.28 \times 10^{11}$at 500 eV

# CONTROL AND DATA ACQUISITION

The beamline is controlled with EPICS (Experimental Physics and Industrial Control System), running on a PXI from National Instruments. There is a graphical user interface in CSS (Control System Studio) to control the beamline parameters and display the multiple device readings.

The data is acquired using different software. For XAS experiments, a phython program using tools from the Py4Syn suit developed at LNLS read the EPICS variables and record to files. The XPS endstation uses a proprietary software SPECSLab2 from SPECS GmBH to control the spectrometer and record data. The XRR uses the software spec for instrument control and data acquisition.

# HOW TO CITE THIS FACILITY

Users are required to acknowledge the use of LNLS facilities in any publications and to inform the Laboratory about any publications, thesis and other published materials. Users must also cooperate by supplying this information upon request.

Support text for acknowledgements:

This research used resources of the Brazilian Synchrotron Light Laboratory (LNLS), an open national facility operated by the Brazilian Centre for Research in Energy and Materials (CNPEM) for the Brazilian Ministry for Science, Technology, Innovations and Communications (MCTIC). The _ _ _ beamline staff is acknowledged for the assistance during the experiments.

# PUBLICATIONS

Scientific publications produced with data obtained at the facilities of this beamline, and published in journals indexed by the Web of Science, are listed below.

Attention Users: Given the importance of the previous scientific results to the overall proposal evaluation process, users are strongly advised to check and update their publication record both at the SAU Online website and at the For the library, updates can be made by sending the full bibliographic data to the CNPEM library (biblioteca@cnpem.br). Publications are included in the database after being checked by the CNPEM librarians and the beamline coordinators.

SGM   SXS

Monfredini, T.; Quitán- Lara, H. M.; Fantuzzi, F.; Wolff, W.; Mendoza, E.; Lago, A. F.; Sales, D. A.; Pastoriza, M. G.; Boechat-Roberty, H. M.. Destruction and multiple ionization of PAHs by X-rays in circumnuclear regions of AGNs, Monthly Notices of the Royal Astronomical Society, v. 488, n. 1, p. 451-469, 2019. DOI: 10.1093/mnras/stz1021

SGM

Pilling, S.; Rocha, W. M.; Freitas, F. M. ; Silva, P. A. da. Photochemistry and desorption induced by X-rays in water rich astrophysical ice analogs: implications for the moon Enceladus and other frozen space environments, RSC Advances, v. 9, n. 49, p. 28823-28840, 2019. DOI: 10.1039/c9ra04585f

SGM   TGM

Nascimento, G. M. do; Pim, W. D. do; Endo, M.; Choi, G. B. ; Kim, Y. A.; Pradie, N. A.; Stumpf, H. O.. Single-wall carbon nanotube modified with copper-oxamate flat complex probed by synchrotron x-ray photoelectron and x-ray absorption spectroscopies, Journal of Molecular Structure, v. 1176, p. 711-717, 2019. DOI: 10.1016/j.molstruc.2018.09.026

SGM

Pancotti, A.; Siervo, A. de; Carazzolle, M. F.; Nascente, P. A. P.; Landers, R.. Surface structure characterization by X-ray photoelectron diffraction of Sn ultra-thin films deposited on Pd(111), Surface Science, v. 685, p. 7-12, 2019. DOI: 10.1016/j.susc.2019.01.014

SGM

Pancotti, A.; Wang, J.; Rezende, A. C. S. A.; Santos, D. P.; Siervo, A. de; Landers, R.; Nascente, P. A. P.. Surface Characterization of NbO Islands Formed on Nb(100) by X-Ray Photoelectron Diffraction, Topics in Catalysis, v. 61, n.9-11, p. 784-791, 2018. DOI: 10.1007/s11244-018-0946-x

PGM   SGM

Moura, C. A. da Silva; Belmonte, G. K.; Segala, M. ; Gonsalves, K. E.; Weibel, D. E.. Polarization Dependence in the Carbon K-Edge Photofragmentation of MAPDST Photoresist: An Experimental and Theoretical Study, Journal of Physical Chemistry C, v. 122, n. 50, p. 28619-28628, 2018. DOI: 10.1021/acs.jpcc.8b07288

MORE PUBLICATIONS