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What is a type of light emission that relies upon a delay between excitation and de-excitation providing an afterglow?
Wiki User
∙ 15y ago
You are talking about a glow-in-the dark material. It is called phosphorescent.
The same idea, light being absorbed and re-emitted at a different frequency - has two main types. If it happens immediately, it is "fluorescent" (think highlighters in a black light) If there is a delay, it is "phosphorescence." Both effects and the delay in the second, are the result of quantum mechanics.
Wiki User
∙ 15y ago
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What are phosphorescent?
These materials absorb light energy in the day and they are able to give off this energy in the dark or at night. Some examples of these materials are glow in the dark stickers, glow in the dark watches and glow in the dark bouncy balls.
Definitions of phosphorescense and fluorescense?
Flourescence is the ability of a material to emit light instantaneously in responses to excitation. Immediately emits light. Phosphorescence is the ability of a material to delay emission of light in response to excitation. Delayed emission of light.
What is Lase?
The lasing threshold is the lowest excitation level at which a laser's output is dominated by stimulated emission rather than by spontaneous emission.
When is atomic absorption more sensitive than atomic emission in atomic absorption spectrometers?
Atomic absorption is more sensitive to atomic emission when the excitation potential is greater than 3.5eV.
Explain why the fluorescence emission spectrum of a polyaromatic molecule in solution mirrors the shape of the absorption spectrum regardless of the excitation frequency?
Generally fluorescence emission spectrum is independent of the excitation wavelength because of the rapid internal conversion from higher energy initial excited states to the lowest vibrational energy level of the excited state
What has the author Carmine John Artura written?
Carmine John Artura has written: 'The spectral distribution of the two-photon emission from the metastable state of singly ionized helium' -- subject(s): Helium, Nuclear excitation, Photon emission, Spectra
Why does the excitation of molecules not take place during the stimulted emission process?
Excitation may not take place in a laser (or the like) for a number of reasons. The lasing medium may be defective or contaminated and unable to lase. The stimulation may be insufficient or incorrect. There are other technical reasons that prevent stimulation emission from taking place, but they generally have to do with the lasing medium or the action of the stimulator. Our friends at Wikipedia have a some relevant articles up, and links are provided. Knowledge there is free.
What two sources of continuous spectra will be use in emission spectroscopy?
Two common sources of continuous spectra used in emission spectroscopy are the electrical discharge lamps and the incandescent lamps. Electrical discharge lamps, such as the mercury vapor lamps, produce continuous spectra due to the excitation of atoms or molecules in the gas discharge. Incandescent lamps, on the other hand, produce continuous spectra because of the thermal emission from the hot filament.
What is the principle behind the working of the spectrofluorometer?
The spectrofluorometer is an instrument which takes one advantage of fluorescent properties of some compounds in order to provide information regarding their concentration and chemical environment in a sample. A certain excitation wavelength is selected, and the emission is observed either at a single wavelength or a scan is performed to record the intensity versus wavelength also called an emission spectra
What is the peak at 800nm in fluorescence spectroscopy?
The peak at 800nm in fluorescence spectroscopy is typically associated with the emission of fluorescence from a sample. At this wavelength, the sample emits light as a result of excitation by a specific wavelength, usually in the visible range of the electromagnetic spectrum. The shape, intensity, and position of the peak can provide insights into the characteristics of the sample, such as its structure, composition, or interactions with other molecules.
How optical absorption spectra is used to detect the presence of molecular species in a gas?
Basically, each molecule has well defined energy levels (vibrational, rotational, ecc.) which are related to the molecule properties like its mass, its length, its symmetry, its moment of inertia and so on. The excitation (deexcitation) of each one of these levels requires the absorption (emission) of some precise amount of energy which can be provided by photons. So, knowing the physical properties of a molecule allows to know at which energies it can absorb or emit photons (electromagnetic radiation). In this way it is possible to excite a gas with a known intensity of photons, at different energies (spectra), and compare it with the resulting intensity of photons emerging from the gas. Observing the resulting peaks of absorption in a Absorbance vs. Energy diagram allows to determine which molecules species are present in the gas.
How does phosphorescence work?
a type of light emission that is the same as fluorescence except for a delay between excitation and de-excitation, which provides an afterglow. The delay is caused by atoms being excited to energy levels that do not decay rapidly. The afterglow may last from fractions of a second to hours, or even days, depending on the type of material, temperature, and other factors.
