Work closer to the Raligh scatter with the Raman Commander. Use the f/4.8 aperture to collect more precious photons. The all reflective optical system works fine in the UV. The double subtractive 350mm focal length pre- monochromator is efficient. There are many available gratings capable of getting you to within 20cm-1. The spectrometer stage can be f/4.7 670-mm when you need the most light or specify f/9.4 1330-mm. The latter provides wonderful symetrical line profiles and resolution of 0.3cm-1.
The Raman Commander is a research tool everyone can use. Reflective optics with optimized coatings provide good efficiency in the ultraviolet (UV.)
Abstract: We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO3, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4eV
B. Schulz1, J. Bäckström, D. Budelmann, R. Maeser, M. Rübhausen, M. V. Klein, E. Schoeffel, A. Mihill and S. Yoon
Abstract: We use resonance Raman scattering (incident photon energies between 1.8 and 4.13 eV), LDA+U calculations, spectroscopic ellipsometry, and oblique IR reflectivity to characterize the strong electron-phonon interactions in the disordered perovskite LaFe0.5Cr0.5O3. When the photon energy coincides with a Cr to Fe Mott-Hubbard transfer gap around 2.4 eV the electron-phonon interaction is manifested by a Franck-Condon effect with exceptional first- and higher order scattering of a local oxygen breathing mode. At higher incident energies we observe a superposition of Franck-Condon scattering and Fröhlich interaction induced infrared active longitudinal optical two-phonon scattering activated mainly by O to Fe charge transfer. Our results establish LaFe0.5Cr0.5O3 as a model compound for research on electron-phonon interactions in strongly correlated complex systems and show that Franck-Condon scattering in complex solids is not limited to Jahn-Teller active compounds.
Jakob Andreasson, Joakim Holmlund, Stefan G. Singer, Christopher S. Knee, Ralf Rauer, Benjamin Schulz, Mikael Käll, Michael Rübhausen, Sten-G. Eriksson, Lars Börjesson, and Alexander Lichtenstein
Abstract: Spin-orbit interaction in Sr2IrO4 leads to the realization of the Jeff=1/2 state and also induces an insulating behavior. Using large-shift Raman spectroscopy, we found two high-energy excitations of the d-shell multiplet at 690 and 680 meV with A1g and B1g symmetry, respectively. As temperature decreases, the A1g and B1g peaks narrow, and the A1g peak shifts to higher energy while the energy of the B1g peak remains the same. When 25% of Ir is substituted with Rh the A1g peak softens by 10% but the B1g peak does not. We show that both pseudospin-flip and non-pseudo-spin-flip d-d electronic transitions are Raman active, but only the latter are observed. Our experiments and analysis place significant new constraints on the possible electronic structure of Sr2IrO4.
Jhih-An Yang, Yi-Ping Huang, Michael Hermele, Tongfei Qi, Gang Cao, and Dmitry Reznik