- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Soft X-ray Absorption Spectroscopy of Aqueous Solutions Using a Table-Top Femtosecond Soft X-ray Source
摘要： We demonstrate the feasibility of soft X-ray absorption spectroscopy in the water window using a table-top laser-based approach with organic molecules and inorganic salts in aqueous solution. A high-order harmonic source delivers femtosecond pulses of short wavelength radiation in the photon energy range from 220 eV to 450 eV. We report static soft X-ray absorption measurements in transmission on the solvated compounds CO(NH2)2, CaCl2, and NaNO3, using flatjet technology. We monitor the absorption of the molecular samples between the carbon (≈280 eV) and nitrogen (≈400 eV) K-edges and compare our results with previous measurements performed at the BESSYII facility. We discuss the roles of pulse stability and photon flux in the outcome of our experiments. Our work paves the way towards table-top femtosecond, solution phase soft X-ray absorption spectroscopy in the water window.
关键词： aqueous solution,high-order harmonic source,flatjet technology,soft X-ray absorption spectroscopy,table-top laser-based approach,femtosecond pulses,water window
更新于2025-09-04 15:30:14
-
Monoisotopic Ensembles of Silicon-Vacancy Color Centers with Narrow-Line Luminescence in Homoepitaxial Diamond Layers Grown in H <sub/>2</sub> –CH <sub/>4</sub> – <sup> [ <i>x</i> ] </sup> SiH <sub/>4</sub> Gas Mixtures ( <i>x</i> = 28, 29, 30)
摘要： Silicon-vacancy (SiV?) color center in diamond is of high interest for applications in nanophotonics and quantum information technologies, as a single photon emitter with excellent spectral properties. To obtain spectrally identical SiV? emitters, we doped homoepitaxial diamond ?lms in situ with 28Si, 29Si, and 30Si isotopes using isotopically enriched (>99.9%) silane SiH4 gas added in H2?CH4 mixtures in the course of the microwave plasma-assisted chemical vapor deposition process. Zero-phonon line components as narrow as ～4.8 GHz were measured in both absorption and luminescence spectra for the monoisotopic SiV? ensembles with a concentration of a few parts per billion. We determined with high accuracy the Si isotopic energy shift of SiV? zero-phonon line. The SiV? emission intensity is shown to be easily controlled by the doped epi?lm thickness. Also, we identi?ed and characterized the localized single photon SiV? sources. The developed doping process opens a way to produce the SiV? emitter ensembles with energy con?ned in an extremely narrow range.
关键词： diamond,silicon-vacancy center,CVD synthesis,optical absorption,photoluminescence,doping,silicon isotope
更新于2025-09-04 15:30:14
-
Group 10 metal–thiocatecholate capped magnesium phthalocyanines – coupling chromophore and electron donor/acceptor entities and its impact on sulfur induced red-shifts
摘要： A new and facile method of generating thiolate groups at the phthalocyanine (Pc) β-position is presented as well the unique properties that these groups confer on the Pc ligand upon coordination of group 10 metals Ni, Pd and Pt(dppe) or SnMe3. In particular, the Q-band is shifted to almost 800 nm for all group 10 metals used, and the complexes show panchromatic absorption owing to new absorbance bands that appear between 400 and 650 nm. Enhanced intersystem-crossing for all transition metal co-ordinated Mg(Pc) complexes was demonstrated by the moderate to very high singlet oxygen quantum yields of 0.36, 0.76 and 0.91 for the Ni, Pd and Pt coordinating complexes, respectively, which show that the heavy metals have direct influence on the Pc π-system and inter-system-crossing (ISC). This was further confirmed by MO calculations, which show mixing of metal and ligand orbitals, as well as suggest that the Q-band transition has both π → π* and ligand-to-metal charge transfer characteristics. Furthermore, the origin of the Q-band red-shift was shown to be due to greater destabilization of the HOMO compared to LUMO/LUMO+1, thus decreasing the HOMO–LUMO band gap.
关键词： thiolate groups,intersystem-crossing,phthalocyanine,MO calculations,HOMO–LUMO band gap,panchromatic absorption,singlet oxygen quantum yields,group 10 metals,Q-band
更新于2025-09-04 15:30:14