Laboratory for micro-Raman
scattering spectroscopy is equipped with triple Jobin Yvon T
64000 spectrometer (gratings with 1800 grooves/mm), a Coherent Ar- Kr
mixed gas ion laser, and a CCD detection system. The set-up contains a
confocal microscope and an x-y-z microscope stage. For variable
temperature measurements there is a Linkam THMS 600 heating and cooling
microscope stage, which allows for the micro-Raman measurements to be
performed within the 77 to 900 K temperature range. Another micro-Raman
set-up is a TriVista 557 spectrometer. A Konti liquid helium microscope
cryostat is also part of this laboratory.
The T64000 monochromator system consists of a double pre-monochromator (stage 1 and 2, see figure 7) and a spectrograph stages (stage 3 in the same figure). The pre-monochromator is a twin monochromator working in a subtractive mode. It acts as a tunable filter in the spectral range defined by the scanning mechanism and the gratings. The spectrograph stage is used as disperser. The T64000 system can be utilized in a triple additive or in a triple subtractive modes. Its unique optical design allows for easy switching between additive and subtractive modes. An additive mode gives the highest spectral resolution and high linear dispersion, whereas a subtractive mode gives a high stray light rejection and allows for collecting low-frequency Raman spectra down to 5 cm-1. The optical diagrams for these two modes are shown in figure:
the triple subtractive mode, which is used more often than the additive
one, a polychromatic radiation enters the first monochromator through
the entrance slit S1 and is dispersed by the grating G1.
The exit slit of the first monochromator (entrance slit of the 2nd
monochromator) Si1/2 selects a bandpass between
The grating G2 in the 2nd monochromator
recombines all the dispersed radiations on the exit slit Si2/3
giving again a polychromatic radiation, but limited to only the spectral
range between l1
In that manner, the elastic radiation remains outside this range, which
is the main purpose of the pre-monochromator. The polychromatic
radiation selected by the pre-monochromator is dispersed by the grating
G3 of the spectrograph and is directed by mirrors to the
lateral exit of the spectrograph. The T64000 is equipped with three
holographic 1800 grooves/mm gratings defining a mechanical range
of 0-950 nm.
The processes of measurement and acquisition are controlled by a LabSpec software. With regard to the efficiency of its detection, the T64000 system makes it possible to gather weak signals. The exposure time and the accumulation number are chosen in order to obtain the best signal to noise ratio.
System technical specification:
Jobin Yvon T 64000 system allows for the measurements of high resolution
Raman spectra to be made in a relatively short time, which makes it
possible that a small content of highly disordered phase in materials be
registered, as it is illustrated in the case of anatase TiO2
or Pr doped CeO2., see below.
The TriVista 557 (S&I GmbH) is a triple spectrograph which offers the highest spectral resolution and extreme stray light rejection required for the Raman and photoluminescence measurements in UV, VIS, and NIR spectral ranges. Its unique optical design (patent pending) allows an easy switching between additive and subtractive modes and it can be easily reconfigured to work as a double or a single spectrometer.
the heart of the TriVista are industry leading Acton Research
Corporation spectrometers. They are known for superb resolution, stray
light rejection, excellent imaging and ruggedness. The TriVista can
operate from 185 nm to 2.2mm.
The spectral resolution can reach 4 picometers in the VIS
spectral range (500 nm). The extreme stray light rejection allows Raman
spectra to be measured as close as 5 wave numbers from the
As it can be seen from the figure above, in triple configuration the Double monochromator stage is used together with the last stage as a Triple system for Raman spectroscopy. However, it can be also used as an excitation stage for Fluorescence and Photoluminescence and the emission can be detected by the last stage of the system.
The S&I software was written to obtain an optimized access to all three stages of the TriVista (Fig. 9). It is programmed in "Visual Basic" and runs in co-operation with the Princeton Instruments' WinSpec software package, which is designed to operate a multitude of CCD detector and allow access to exclusive detector functions. The S&I software controls spectrometer functions while the WinSpec is used as a DLL and provides data acquisition and setup functions for multi-channel detectors.
The TriVista spectrometer is equipped
with the Princeton Instruments Spec-10: 256
detector (Fig.10), which is a fully integrated spectroscopic
CCD system. A choice of industry standard, spectroscopic-format E2V
sensors are offered. The Spec-10: 256E incorporates an open electrode
sensor which offers a broadband response over a wide spectral region -
from 200 to 1050 nm, as can be seen from the quantum efficiency curve in
the Fig. 11. The liquid nitrogen cooling of the CCD effectively
eliminates dark noise, even for long exposures.
simultaneously obtain Stokes and Anti-Stokes Raman spectra (see
Fig. 12), the TriVista system is equipped by a laser mask (Fig.13) which
can be installed on 1st , 2nd, or on both
intermediate slits. The laser mask is a very thin metal bar positioned
precisely in the middle of the slit which mechanically blocks the laser
light. For more versatility, the laser stop mask has 4 options - three
bars of different width (150, 300, -600
mm) and the open space to allow
the Raman signal to pass unblocked through the intermediate slit. The
laser stop mask is set on a sliding strip for changing between 4 options
and a precise positioning.
The Micro-Raman assembly is based on the upright microscope BX51 from Olympus and the Confocal Micro-Raman Interface (CMRI) as an extension for the BX51 to allow for the Micro-Raman Spectroscopy. CMRI is designed to allow direct coupling and fibre coupling for transmission of a laser beam and a Raman signal. Polarisation dependent measurements are possible for both direct coupled and fibre coupled laser beams. The confocal Raman microscope has a spatial resolution on a micron scale.
The TriVista system is equipped with a CCD detector, a confocal
microscope, whereas the software-driven XYZ stage
makes possible an automated 3D mapping
with an auto focus option. For variable temperature measurements under
microscope we have supplied Linkam THMSG600 heating/freezing stage which
works in temperature range -196° to 600°C, up to 130°C/min heating and
temperature stability <0.1°C.
The THMS600 is one of the most popular heating and freezing stages used in many applications where high heating/freezing rates and 0.1°C accuracy and stability are needed. The LINKAM THMS600 heating/cooling stage is equipped with a CI94 temperature controller and a LNP94 Liquid Nitrogen Pump.
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