Work plan of OPSA project consists of 7 workpackages + Management workpackage. Detailed description of each of them is given as follows:

WP1 and WP2 

The main results of the project that should be realized are the upgrade or renew of the present equipment for Raman (photo-luminescence) spectroscopy and Fourier - transform infrared spectroscopy. In the first case it is necessary to replace the existing system with triple micro-Raman spectrometer equipped with a CCD multi channel detection system. 

In the case of the FT spectrometer the present spectral range (30-5000 cm^-1) should be extended to the near infrared and visible region (up to 25000 cm^-1=400nm). Beside these improvements, FT-spectrometer will be equipped with IR microscope in order to perform measurements on microscopic samples. For measurements at liquid helium temperature it is necessary to purchase a low-vibration closed cycle cryostat since there is no helium liquefier in Serbia. In order to carry out measurements on the nano (micro) scale materials appropriate microscopes will be needed as it is already included in this project proposal. 

Raman spectroscopy as a method of vibrational spectroscopy comes to be of significant importance for the characterization and determination of vibrational properties of amorphous and crystalline nanosized phases. Raman scattering measurements can provide information on the local atomic arrangement and short-range order in nano systems and can be used to characterize also porous nano structures. From the changes in the Raman peak position and linewidth with respect to the bulk materials one can get an information about the grain-size effects and the size distribution of nano particles, about defects/ disordered states, microstrains and Grüneisen parameter of the low dimensional systems, phase transitions in quantum systems, dopant concentration in semiconductor nano materials and about local field effects in dot-matrix interactions (strain–induced shifts of the LO phonon bands).

The existing Raman system in Institute of Physics (the same system is used for photoluminescence spectroscopy measurements) is set up in late eighties and it is amortized long ago. It is equipped with double grating U1000 Jobin Yvon spectrometer, Ar, Kr, He-Cd, He-Ne, ion lasers, and classical RCA photomultiplier as a detection system. The system contains a macro-Raman optical facility, and allows the measurements in the temperature range between 10 and 400 K.

Simple replacement of photomultiplier (PMT) with CCD detector in existing U1000 Raman spectrometer is not possible without substantial modifications. Namely, a set of changes should be necessarily done, like changing of internal slits, removing exit slit, development of opto-mechanical coupling at the entrance slit for microscope set-up, etc. At the end, we will have double monochromator (M) with CCD (desired sensitivity level) and microscope, but with worse stray light rejection, the condition which is very important for Raman spectrometers. This problem is usually solved by adding one more stage (fore-monochromator - FM). Adding of FM would lead to additional reconstruction of our U1000 monochromator, which includes optical and mechanical coupling between M and FM, development of new software, etc. Finally, as a result of such improvement, we will alter the performances of existing system and realize new system, but its performances will be far from modern micro-Raman spectroscopy set-ups. Analysing the Raman scattering market we decided to buy TriVista 557 triple stage system, equipped with CCD detector and confocal microscope.

The TriVista is the most flexible system for scientific use on the market. Three imaging corrected spectrometers of 500 mm and 750 mm focal length yield an excellent stray light rejection with best resolution. The optical design enables to switch between additive mode and subtractive mode without an additional optic. The working range of the TriVista is from UV to NIR, depending on the grating and detector selection. Modular concept of this system offers several possibilities for optical measurements as it is shown in the figure below. Thus, the Double Monochromator Stage can be used together with the last stage as a Triple system for Raman Spectroscopy. 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. To carry out Pico- or Femptosecond spectroscopy the second spectrograph may be mounted turned around for 180°. So the first two stages compensate the different travel time of different wavelength. Last but not least, the system enables three experiments to be run at once. All exits can be occupied by Single Channel Detectors like photo multiplier, diodes and as well by Multichannel Detectors like CCD cameras or NIR/IR Array detectors. Assembling of different detectors at a time leads to easy switch between scanning photon counting option and complete spectral detection.
 

An illustration of different configurations which can be realized using TriVista system
	Triple Raman Spectrometer in additive or subtractive mode with entrance slit, Macro- or Micro-Chamber
	Double monochromator,additive or subtractive mode and single monochromator
	Three monochromators for three simultaneous experiments
	Photoluminescence & fluorescence

In the first year of the OPSA project we obtained triple Raman system (TriVista 557) equipped with CCD-detector, confocal microscope and microscope cryostat) for completing of the Raman set-up. Second year of the project is dedicated to integration, installation and testing of the system, and the last year is foreseen for training.

Fourier transform infrared spectroscopy (FTIR) provides information complementary to Raman spectroscopy. Studying transversal and surface optical phonon modes of nano particles and comparing them with those of the corresponding bulk material it is possible to obtain information about: 1) crystallinity; 2) size-confinement effects; 3) interatomic bonds; 3) chemical nature of the surface bonds and surface groups; 4) possible presence of the contaminating species on the nano particles surface and surface reactions; 5) porosity of the nano material. An accurate description of the vibrational modes of the nano crystalline materials is essential to understand the coupling of vibrational modes to electronic charge i.e. electron-phonon interaction. It is a useful technique for the band gap studies of narrow gap semiconductor nano materials and photonic crystals structures and devices. 

The present FTIR system (Bomem DA-8 Fourier transform far infrared spectrometer) enables reflectance and transmittance measurements of crystalline and amorphous nano-sized materials and structures in a spectral range from 30 to 5000 cm^-1. Upgrade of this system with adequate light sources, beam splitters and detectors for near IR and visible region, an IR microscope and a closed cycle cryostat is necessary step for the characterization of materials from far-infrared to ultraviolet (400 nm) spectral region. 

As in the case of Raman set-up, in the first year of the project we have ordered all necessary components for completing of FT-spectrometer. Second year of the project is dedicated to integration, installation and testing of the system, and the last year is foreseen for  training.

WP3 and WP4 

We are planning training of some of our co-workers in the field of micro-Raman and micro-PL spectroscopy at low temperatures, high pressure and high magnetic fields at the Institute of Materials Science of the University of Valencia, and Technical University of Athens. Training in the field of the Fourier-transform optical spectroscopy will be conducted at Max Planck Institute for Solid State Physics, Stuttgart, Germany, and/or at University of Leoben, Austria.

WP5

WP6

WP7