Two-Dimensional Pigment Monolayer Assemblies for Light-Harvesting Applications:  Structural Characterization at the Air/Water Interface with X-ray Specular Reflectivity and on Solid Substrates by Optical Absorption Spectroscopy

1997 ◽  
Vol 101 (11) ◽  
pp. 2006-2019 ◽  
Author(s):  
Brian W. Gregory ◽  
David Vaknin ◽  
John D. Gray ◽  
Ben M. Ocko ◽  
Pieter Stroeve ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Structural Characterization ◽  
Optical Absorption Spectroscopy ◽  
Water Interface ◽  
Two Dimensional ◽  
X Ray ◽  
Solid Substrates ◽  
Air Water Interface ◽  
Specular Reflectivity

H-bonding scheme in allactite: a combined single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, FTIR and EPMA-WDS study

2016 ◽  
Vol 80 (5) ◽  
pp. 719-732 ◽  
Author(s):  
G. Diego Gatta ◽  
Ferdinando Bosi ◽  
Maria Teresa Fernandez Diaz ◽  
Ulf Hålenius
Keyword(s):  
Neutron Diffraction ◽  
Optical Absorption ◽  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Optical Absorption Spectroscopy ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Bonding Scheme

AbsatractThe crystal chemistry of allactite from Långban, Värmland (Sweden) was investigated by single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and electron microprobe analysis by wavelength-dispersive spectroscopy (EPMA-WDS). The optical spectra indicate the presence of Mn in valence state 2+ only. Assuming 16 O atoms per formula unit, arsenic as As5+and the (OH) content calculated by charge balance, the resulting formula based on the EPMA-WDS data is (Mn2+6.73Ca0.13Mg0.12Zn0.02)∑7.00(As5+)2.00O16H8, very close to the ideal composition Mn7(AsO4)2(OH)8. In the unpolarized FTIR spectrum of allactite, fundamental (OH)-stretching bands are observed at 3236, 3288, 3387, 3446, 3484, 3562 and 3570 cm–1, suggesting that a number of OH environments, with different hydrogen bond strengths, occur in the structure. The neutron structure refinement shows that four independent H sites occur in allactite with full site occupancy, all as members of hydroxyl groups. The complex hydrogen-bonding scheme in the allactite structure is now well defined, with at least nine hydrogen bonds energetically favourable with mono-, bi- and trifurcated configurations.

Structural Characterization of a Covalent Monolayer Sheet Obtained by Two-Dimensional Polymerization at an Air/Water Interface

2017 ◽  
Vol 129 (48) ◽  
pp. 15464-15468 ◽  
Author(s):  
Vivian Müller ◽  
Feng Shao ◽  
Milos Baljozovic ◽  
Mina Moradi ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Water Interface ◽  
Two Dimensional ◽  
Air Water Interface

Structural Characterization of a Covalent Monolayer Sheet Obtained by Two-Dimensional Polymerization at an Air/Water Interface

2017 ◽  
Vol 56 (48) ◽  
pp. 15262-15266 ◽  
Author(s):  
Vivian Müller ◽  
Feng Shao ◽  
Milos Baljozovic ◽  
Mina Moradi ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Water Interface ◽  
Two Dimensional ◽  
Air Water Interface

scholarly journals Two-dimensional monitoring of air pollution in Madrid using a Multi-AXis Differential Optical Absorption Spectroscopy two-dimensional (MAXDOAS-2D) instrument

2021 ◽  
Vol 14 (4) ◽  
pp. 2941-2955
Author(s):  
David Garcia-Nieto ◽  
Nuria Benavent ◽  
Rafael Borge ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Air Quality ◽  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Urban Areas ◽  
Spatial Information ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Two Dimensional ◽  
Inversion Algorithm ◽  
The City

Abstract. Trace gases play a key role in the chemistry of urban atmospheres. Therefore, knowledge about their spatial distribution is needed to fully characterize air quality in urban areas. Using a new Multi-AXis Differential Optical Absorption Spectroscopy two-dimensional (MAXDOAS-2D) instrument, along with an inversion algorithm (bePRO), we report the first two-dimensional maps of nitrogen dioxide (NO2) and nitrous acid (HONO) concentrations in the city of Madrid, Spain. Measurements were made during 2 months (6 May–5 July 2019), and peak mixing ratios of 12 and 0.7 ppbv (parts per billion by volume) for NO2 and HONO, respectively, were observed in the early morning in the southern part of the downtown area. We found good general agreement between the MAXDOAS-2D mesoscale observations – which provide a typical spatial range of a few kilometers – and the in situ measurements provided by Madrid's air quality monitoring stations. In addition to vertical profiles, we studied the horizontal gradients of NO2 in the surface layer by applying the different horizontal light path lengths in the two spectral regions included in the NO2 spectral analysis: ultraviolet (UV, at 360 nm) and visible (VIS, 477 nm). We also investigate the sensitivity of the instrument to infer vertically distributed information on aerosol extinction coefficients and discuss possible future ways to improve the retrievals. The retrieval of two-dimensional distributions of trace gas concentrations reported here provides valuable spatial information for the study of air quality in the city of Madrid.

Structure and excited-state dynamics of dimeric copper(i) photosensitizers investigated by time-resolved X-ray and optical transient absorption spectroscopy

2021 ◽  
Vol 23 (5) ◽  
pp. 3656-3667
Author(s):  
Lucía Velasco ◽  
Leonel Llanos ◽  
Pedro Levín ◽  
Andrés Vega ◽  
Jin Yu ◽  
...  
Keyword(s):  
Excited State ◽  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Time Resolved ◽  
X Ray ◽  
Solvent Type ◽  
Optical Transient

Three homoleptic Cu(i) dimeric photosensitizers are studied through ultrafast X-ray and optical absorption spectroscopy. The complexes show distinct excited state lifetimes, due to the solvent type and spacers' flexibilities between the Cu centres.

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