Search results for "Raman-spektroskopia"
showing 5 items of 5 documents
Simultaneous non-invasive gas analysis in artificial photosynthesis reactions using rotational Raman spectroscopy
2022
Optimising reactions in artificial photosynthesis research requires screening of many reaction and operation parameters, which is often resource-intense and time-consuming. In this paper, we demonstrate the use of a rotational Raman-based spectrometer for non-invasive quantification of several gases (H2, O2, N2, CO, CO2) with short analysis times (15 s), enabling high throughput screening. Furthermore, with this device, reaction progress can be monitored in situ, by real-time simultaneous quantification of multiple gases. We have applied this instrument and developed a method to study the O2 dependency of a prototypic light-driven hydrogen evolution reaction, showcasing the value of this ap…
Making Graphene Luminescent by Direct Laser Writing
2020
Graphene is not intrinsically luminescent, due to a lack of bandgap, and methods for its creation are tricky for device fabrication. In this study, we create luminescent graphene patterns by a simple direct laser writing method. We analyze the graphene using Raman spectroscopy and find that the laser writing leads to generation of line defects after initial formation of point defects. This Raman data enables us to create a model that explains the luminescence by a formation of small domains due to confinement of graphene by line defects, which is conceptually similar to the mechanism of luminescence in graphene quantum dots. peerReviewed
Computational investigations on rotational and vibrational spectroscopies of some diatomics in solid environment
2013
In this thesis, spectroscopic and structural properties of homogeneous para-hydrogen crystals and diatomic molecules embedded in rare gas crystals are explored by theoretical means. The agreement with experimental signatures indicates the suitability of the chosen quantum and classical methods to accurately describe the various low-temperature physical and chemical problems investigated at the laser laboratory. A novel explanation of band structures in Raman and IR spectra is given for CO in Ar. Rotational transition rules are found to dictate the spectral broadening of infrared and Raman band structures as a function of temperature. The results show that after photodissociation of matrix-i…
Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y = Br, Cl; bdmim = 1-butyl-2,3-dime…
2014
The discrete mixed [TeBrxCl6−x]2− anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X = Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X = Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4]2− and [TeBr4Cl2]2− anions …
Laserspektroskopia mineraalianalytiikassa : nopeasti ja tehokkaasti monipuolista informaatiota mineraaleista
2022
Laserspektroskopiset menetelmät ovat nopeita ja tehokkaita mineraalitutkimuksen keinoja, koska analyysi voidaan tehdä suoraan näytteen pinnalta ja jopa metrien päästä kohteesta. Nykyteknologian ansiosta laserspektroskopian laitteistoja voidaan lisäksi miniatyrisoida, ja siten ne soveltuvat etämittauksiin esimerkiksi maastossa, linjastolla tai kaivoksessa (in situ). Tässä artikkelissa esitellään laserindusoitu plasmaspektroskopia (LIBS), laser-indusoitu luminesenssispektroskopia ja Raman-spektroskopia, joilla saadaan näytteistä toisiaan täydentävää informaatiota (Romppanen 2021). Tunnetuimmat esimerkit laserspektroskopian soveltuvuudesta mineraalianalytiikassa löytyvät Marsista, sillä planee…