Search results for "quantum yield"

showing 3 items of 163 documents

Sunlit surface waters : exploring the photochemical reactivity of dissolved organic carbon

2017

In surface waters, solar radiation can photochemically mineralise the dissolved organic carbon (DOC, a measure of dissolved organic matter, DOM) to dissolved inorganic carbon (DIC). This DIC photoproduction constitutes an essential yet vague flux in the aquatic carbon cycling. The present thesis is based on the empirical assessment of the DOC photochemical reactivity, which was determined as the spectral apparent quantum yields (AQY) for DIC photoproduction. First, AQYs were determined in DOM solutions to quantify the impact of pH and DOM-associated iron. Then boreal lake waters were used for assessing the alteration of DOC photoreactivity due to water quality and catchment property. By sim…

liuennut orgaaninen hiiliboreal lakescatchment land userautadissolved organic matterreaktiivisuusvedenlaatuapparent quantum yieldsphotomineralisationwater qualityjärvetmineralisaatioironboreaalinen vyöhykepintavesiorgaaninen ainesvalokemiaauringonsäteily
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KOSMOS 2017 Peru Side Experiment: nutrients, phytoplankton abundances, enzyme rates, photophysiology

2022

This data was collected during an short-term incubation experiment in March 2017 that investigated the response of a surface plankton community to upwelling. This experiment was carried in the framework of the SFB754-funded KOSMOS mesocosm study that took place in La Punta, Callao, Peru between February-April 2017. A total of six different treatments were used to disentangle chemical and biological characteristics of deep water that influence surface plankton blooms: 2 different deep water sources with different nutrient concentrations; 3 treatments to distinguish the effects of inorganic nutrients, organic nutrients and deep water microbial populations. Measured variables include inorganic…

ratioDay of experimentSFB754colored dissolved organic matter at 325 nmNitriteChlorophyll aAbsorption coefficient colored dissolved organic matter at 254 nmClimate - Biogeochemistry Interactions in the Tropical Ocean (SFB754)colorimetric determinationFluorometerFluorometricNitrateNanoplanktonPhytoplankton cells phycocyanin-containing (FL-4)PicoeukaryotesFluorometer fast repetition rateCalculatedFlow cytometryNutrient consumption ratioforward scatterSynechococcusupwelling systemsMesocosm experimentSpectrophotometricClimate Biogeochemistry Interactions in the Tropical Ocean SFB754SilicateBiogeochemistryBiospheric SciencesMaximum photochemical quantum yield of photosystem IIenzyme activitycell sizeDissolved inorganic nitrogen/dissolved inorganic phosphorus ratioKOSMOS_2017chainsAbsorption coefficient colored dissolved organic matter 250 nm/365 nm ratioeastern tropical South Pacific OceanKOSMOSExcess phosphateAbsorption coefficient colored dissolved organic matter at 325 nmNatural SciencesGeosciencescolored dissolved organic matter at 254 nmphycocyanin containing FL 4Absorption coefficientPhosphateTank numberPhytoplankton cells chainsNetwork of Leading European AQUAtic MesoCOSM Facilities Connecting Mountains to Oceans from the ArctReplicatenutrientsfast repetition rateDATE TIMECryptophytesMicrophytoplanktonPhytoplankton cellsLeucine aminopeptidase activityDissolved inorganic nitrogen dissolved inorganic phosphorus ratiofungiEnzymatic assayContinuous flow analyserTreatmentDATE/TIMEcolored dissolved organic matter 250 nm 365 nmPhytoplanktonPhytoplankton cell size forward scatterNetwork of Leading European AQUAtic MesoCOSM Facilities Connecting Mountains to Oceans from the Arctic to the Mediterranean (AQUACOSM)CDOMContinuous flow analyser colorimetric determinationNitrate and Nitrite
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Role of Vibrational Dynamics in Electronic Relaxation of Cr(acac)3

2015

Ultrafast energy relaxation of Cr(acac)3 dissolved in tetrachloroethylene (TCE) is studied by time-resolved infrared (TRIR) spectroscopy by using electronic and vibrational excitation. After electronic excitation at 400 or 345 nm, the ground state recovers in two time scales: 15 ps (major pathway) and 800 ps (minor pathway), corresponding to fast electronic transition to the ground state and intermediate trapping on the long-lived (2)E state followed by intersystem crossing (ISC) to the ground state. The quantum yield for the fast recovery of the ground state depends on the excitation wavelength, being higher for 345 nm. Vibrational cooling (VC) occurs on the electronic excited states with …

ta114ChemistryRelaxation (NMR)kinetic modelsQuantum yieldMolecular physicsMolecular electronic transitiontransition metal complexesvibrationsIntersystem crossingComputational chemistryExcited statePhysical and Theoretical ChemistryGround stateSpectroscopyta116ExcitationThe Journal of Physical Chemistry A
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