Excited State Population
Excited State Population - Related Videos
14:47
Population Growth - Student Protocol
0 Views •
2019
Exponential Population Growth Model ExpandNOTE: In these experiments you will use computer software to simulate different types of growth models. HYPOTHESES: The experimental hypothesis might be that if we increase either R, the reproductive rate or the initial population size, NT, that this will increase the population size after 10 generations in an exponential growth model compared to unmanipulated control populations. The null hypothesis may be that populations of different R and initial...
04:45
Population Growth - Concepts
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2019
Population Models An ecological population is a group of individuals of a single species living in an area at the same time. To persist, a population must either grow or maintain its size. Population ecology is the study of how population size and age distribution change over time through interactions with other species and the environment as well as with individuals of their own species. A particularly important feature that is studied by ecologists is the rate at which a population grows or...
02:04
Conservation of Small Populations
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2019
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
04:31
Side Population Assay: A Method to Isolate Side Population of Tumor Cells from Zebrafish
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2023
The following protocol describes a method for isolating the side population of T-cell Acute Lymphoblastic Leukemia (T-ALL) tumor cells, consisting of stem cells, from an adult Zebrafish. The side population lacks prominent cell markers and hence we use Hoechst 33342 dye efflux assay to isolate them.
12:33
Corticospinal Excitability Modulation During Action Observation
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Cited by 22 •
2013
Single-pulse transcranial magnetic stimulation over the primary motor cortex, neuronavigation, and registration of electromyographic activity of hand muscles were used in this study to explore corticospinal excitability while participants were observing action sequences.
FAQs
Excitation wavelength determines which energy-level transitions can be reached. When the photon energy aligns with a molecule’s available spacing between levels, it can increase population in the corresponding excited state. Changing the wavelength can therefore alter the relative populations of electronic, vibrational, or rotational states, which in turn changes the absorption or emission features observed.
These relaxation pathways remove particles from excited levels at different rates and by different mechanisms. Fluorescence and phosphorescence release energy as light, whereas nonradiative decay releases it without photon emission. Their competition determines how long an excited population persists and whether the resulting signal is dominated by fluorescence, phosphorescence, or reduced light emission.
Temperature affects how particles are distributed among available energy levels, while energy-level spacing determines the energy required to reach each level. Together, these factors influence which excited states can become populated and in what relative amounts. Their effects are important when interpreting spectra or comparing molecular systems with different electronic, vibrational, or rotational structures.
Absorption spectra indicate which energy transitions are being accessed, while emission spectra show how populated excited states lose energy. Comparing these signals helps identify the influence of excitation wavelength, level spacing, and relaxation pathways. The resulting spectral information can clarify whether a system is undergoing fluorescence, phosphorescence, or substantial nonradiative decay.
A basic investigation selects an excitation wavelength, exposes the molecular or atomic system to that energy, and measures the resulting absorption or emission response. Researchers can then compare signals under different wavelengths or temperatures and consider fluorescence, phosphorescence, and nonradiative decay. This workflow connects measured spectra with changes in the occupied energy levels.
Control is useful when researchers need to influence absorption, emission, photochemical reactions, or energy transfer. Adjusting excitation conditions and relaxation behavior can change which states are occupied and how long they persist. These principles support work in molecular spectroscopy, solar energy conversion, fluorescence imaging, atmospheric chemistry, and light-responsive material design.
Laser action depends on controlling populations among energy levels so that light emission can be produced, while photochemical reactions depend on molecules reaching electronically excited states that can participate in subsequent processes. Studying the population and relaxation of those states helps connect energy absorption to observable emission, chemical reactivity, and energy-transfer behavior.