scholarly journals Enhancements to and Characterization of the Very Early Time Electromagnetic (VETEM) Prototype Instrument and Applications to Shallow Subsurface Imaging at Sites in the DOE Complex

2000 ◽  
Author(s):  
David L Wright ◽  
Weng Cho Chew
Keyword(s):  
Early Time ◽  
Subsurface Imaging ◽  
Shallow Subsurface ◽  
Prototype Instrument

scholarly journals Delineating shallow Neogene deformation structures in northeastern Pará State using Ground Penetrating Radar

2003 ◽  
Vol 75 (2) ◽  
pp. 235-248 ◽  
Author(s):  
Dilce F. Rossetti
Keyword(s):  
Ground Penetrating Radar ◽  
Structural Models ◽  
Field Studies ◽  
Strike Slip ◽  
Brittle Deformation ◽  
Shallow Subsurface ◽  
Deformation Structures ◽  
Ground Penetrating ◽  
Slip Motion

The geological characterization of shallow subsurface Neogene deposits in northeastern Pará State using Ground Penetrating Radar (GPR) revealed normal and reverse faults, as well as folds, not yet well documented by field studies. The faults are identified mostly by steeply-dipping reflections that sharply cut the nearby reflections causing bed offsets, drags and rollovers. The folds are recognized by reflections that are highly undulating, configuring broad concave and convex-up features that are up to 50 m wide and 80 to 90 ns deep. These deformation structures are mostly developed within deposits of Miocene age, though some of the faults might continue into younger deposits as well. Although the studied GPR sections show several diffractions caused by trees, differential degrees of moisture, and underground artifacts, the structures recorded here can not be explained by any of these ''noises''. The detailed analysis of the GPR sections reveals that they are attributed to bed distortion caused by brittle deformation and folding. The record of faults and folds are not widespread in the Neogene deposits of the Bragantina area. These GPR data are in agreement with structural models, which have proposed a complex evolution including strike-slip motion for this area from the Miocene to present.

scholarly journals Relaxation Dynamics of Chlorophyll b in the Sub-ps Ultrafast Timescale Measured by 2D Electronic Spectroscopy

2020 ◽  
Vol 21 (8) ◽  
pp. 2836
Author(s):  
Elisa Fresch ◽  
Elisabetta Collini
Keyword(s):  
Internal Conversion ◽  
Electronic Spectroscopy ◽  
Early Time ◽  
Relaxation Processes ◽  
Ultrafast Dynamics ◽  
Chlorophyll B ◽  
Relaxation Dynamics ◽  
Biologically Relevant ◽  
Harvesting Systems

A thorough characterization of the early time sub-100 fs relaxation dynamics of biologically relevant chromophores is of crucial importance for a complete understanding of the mechanisms regulating the ultrafast dynamics of the relaxation processes in more complex multichromophoric light-harvesting systems. While chlorophyll a has already been the object of several investigations, little has been reported on chlorophyll b, despite its pivotal role in many functionalities of photosynthetic proteins. Here the relaxation dynamics of chlorophyll b in the ultrafast regime have been characterized using 2D electronic spectroscopy. The comparison of experimental measurements performed at room temperature and 77 K allows the mechanisms and the dynamics of the sub-100 fs relaxation dynamics to be characterized, including spectral diffusion and fast internal conversion assisted by a specific set of vibrational modes.

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