Conditions Extrêmes et Matériaux : Haute Température et Irradiation
CEMHTI - UPR3079 CNRS

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Very High Temperature RAMAN spectroscopy (Tmax above 2000K)

Disorder and Optical Properties
patrick.simon@cnrs-orleans.fr  Patrick Simon   [+33](0)238 25 55 21

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introduction

this device - dedicated to experimental measurements in non routinely experimental conditions - is based on an advanced research Raman system ( HORIBA Jobin Yvon T64000). It provides excellent resolutions (as low as 0.15 cm-1), gives access to very low wavenumbers (as low as a few cm-1 for no less than a ten of excitation wavelength). In addition, an original system of temporal resolution allows studies at very high temperatures (up to 2500 K)

excitation

We have two lasers offering several wavelenghs for sample excitation:

  • continuous : Ar/Kr Coherent Innova 90 C (main wavelengths : 457, 488, 514, 598, 647 nm)

  • pulsed Nd:YAG doubled Spectra Physics laser (532 nm, 30 ns, 1-15kHz)

dispersion configurations

The triple Raman spectrometer, with confocal microprobe and high stray light rejection, allows three different configurations :

  • triple subtractive (1 on the following figure): the two pre-monochromator’s gratings are used to remove the Rayleigh light contribution by using an intermediary slit to stop the unwanted light. The inelastic scattered truncated beam is then analyzed thanks to the monochromator. We easily obtain a 10 cm-1 low wavenumber limit in backscattering configuration.

  • triple additive (2 on the following figure): the three grating’s dispersions are summed up in ordre to obtain the best spectral resolution, as low as 0.13 cm-1 (at 647 nm).

  • simple (3 on the following figure): The light is directly sent to the monochromator without entering the pre-monochromator. A Notch or edge filter is then used to “cut” the Rayleigh light. This configuration gives the most intense Raman signal


schema T64000

detection

the setup allows the choice between two CCD detectors: when working in continuous mode, a LN2 cooled detectors is used. When working in time time resolved configuration, an intensified CCD is available (4 on the previous figure)

heating stage
  • Linkam TS 1500 heating stage : allows a RT to 1500 °C controlled atmosphere sample environment

  • Linkam THMS 600 heating stage : allows a -196 to 600 °C controlled atmosphere sample environment

  • Linkam 1400 XY heating stage : allows a RT to 1400 °C controlled atmosphere sample environment with fast cooling option (up to 240 °C/min for quenching effect studies)





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