# OVERVIEW

BACK

The TGM (Toroidal Grating Monochromator) beamline is dedicated to ultraviolet spectroscopy techniques in the energy range of 3 to 330 eV (ca. 400 to 4 nm). At this energy range, it is possible to perform studies related to the electronic structure and luminescence properties of solids, as well as on gas and solids subjected to conditions mimicking the atmospheric and astrophysical environments.

The TGM beamline was the first beamline to be built and made available for the users` community at the UVX storage ring of LNLS, and it has been in continuous operation since 1997. It is a spectroscopy beamline, based on a 1.67T bending magnet. It has a monochromator with three toroidal gratings and currently operates from 3 eV (413.28 nm) to 330 eV (3.75 nm), in ultra-high vacuum conditions. To ensure energy purity on the spectrum, it counts with a differentially-pumped gas filter (He, Ne, Ar, Kr), with different upper-energy cutoffs on the ionization threshold of the gases (24.6, 21.6, 15.7 and 14.1 eV, respectively), in addition to solid-state filters (glass, quartz and MgF2) for lowers energies (4.1, 8.2, 10.9 eV, respectively). Above 50 eV, the geometry of the beamline acts as an efficient cutoff of higher harmonics.

This beamline covers an important range of energy for studies of X-ray absorption of very light elements such as the K-edge of Li and the L-edge of environmentally significant ones (P, S, Cl, K). It is possible to directly assess the electronic structure of semi-conductors and insulators, to measure the luminescence of solids, photodegradation and photoionization of polymers and biomolecules, simulation of space and astrophysical conditions, and to do mass spectrometry.

Future planned experimental stations for this beamline include a Photoemission Microscope (PEEM), Circular Dichroism on the UV, for structural biology, and a dedicated chamber for optical measurements, including a setup for cryogenic studies.

## CONTACT

Beamline Email: N/A

Beamline Telephone Number: +55 19 3512 1140

Coordinator: Douglas Galante

Coordinator Email: douglas.galante@lnls.br

Coordinator Telephone Number: +55 19 3517 5081

For more information on the Beamline Team, check out the Beamline Team’s page here

# OPTICAL ELEMENTS

ElementTypePosition[m]Description
SOURCEBending Magnet-Bending Magnet D05 exit A (4°), 1.67T,
M1Toroidal focusing mirror-R = 93.23m
MonochromatorToroidal gratings, grazing incidence-Grating 1: 3 – 13 eV (Pt, 75 l/mm) Grating 2: 13 – 100 eV (Au, 200 l/mm) Grating 3: 100 – 330 eV (Au, 1800 l/mm)
M2Toroidal focusing mirror-R = 139.16m
M3Toroidal focusing mirror-R = 74.00m
Harmonics filtersGas and solids-Differentially pumped ​gas filter (up to 24.59 eV) Solid state filters: Glass, quartz and $\rm MgF_{2}$ windows

# PARAMETERS

ParameterValueObs. | Condition
Energy range [eV]3 - 330-
Energy resolution [$\Delta$E/E]500 -700effective
Beam size at sample [$\rm mm^{2}$, FWHM]1.02mm X 0.5mm
Flux density at sample [ph/s/$\rm mm^{2}$]$10^{9}$at 10 eV
Flux density at sample [ph/s/$\rm mm^{2}$]$5 \times 10 ^{11}$whitebeam
Polarization control-Entrance polarization slits (upper and lower)
to use natural polarization.

# INSTRUMENTATION

InstrumentTypeModelSpecificationsManufacturer
DetectorPhotomultipliersR928 R316 R594-Hamamatsu
DetectorSilicon Photomultiplier (Si-PM)S13360-3025CS-Hamamatsu
DetectorEmission spectrographQE65000-Ocean optics
DetectorTotal electron Yield (TEY)6514 and 6485-Keithley
DetectorVUV ionization chamber---
SpectrometerMicro-Raman for off-line measurementsinViaExcitation lasers: 532, 633 and 785nm; Detector: CCD; Fast 2D and 3D mapping system; Fiber optics proves for in-process measurements; 5, 20, 50 and 100X objectives; Linkam temperature cell (-196°C – 600°C)Renishaw

# CONTROL AND DATA ACQUISITION

The beamline is controlled by EPICS, under Linux based systems, with most of the scripts in Python and a user-friendly graphic interface.

# APPLYING FOR BEAMTIME

Currently, the beamline is accepting proposals only for long-term projects. Please, contact directly the beamline coordinator for additional details.