A Time-Resolved Fluorescence Experiment for Physical Chemistry
... Many molecules re-emit some of the light energy they have absorbed as light, but delayed in time and at a different energy than the absorbed light. This is usually referred to as fluorescence or phosphorescence. As shown in figure 1, fluorescence is the emission of light by a molecule in the same el ...
... Many molecules re-emit some of the light energy they have absorbed as light, but delayed in time and at a different energy than the absorbed light. This is usually referred to as fluorescence or phosphorescence. As shown in figure 1, fluorescence is the emission of light by a molecule in the same el ...
JGOFS report Nr. 27 - Joint Global Ocean Flux Study
... losses are equal is called the 'compensation depth' (zero net photosynthesis). The 'euphotic zone' is the portion of the water column that supports net primary production. In this regard it is important to point out that the respiratory costs for the calculation of the compensation depth are for the ...
... losses are equal is called the 'compensation depth' (zero net photosynthesis). The 'euphotic zone' is the portion of the water column that supports net primary production. In this regard it is important to point out that the respiratory costs for the calculation of the compensation depth are for the ...
Applications for CdSe Quantum Dots
... emission is typically narrower than that of inorganic phosphorus currently used as wavelength conversion materials.3 Quantum dots absorb light from wavelengths shorter then their absorbance edge and then emit light at their luminescence peak wavelength. For example, commercially available gallium ni ...
... emission is typically narrower than that of inorganic phosphorus currently used as wavelength conversion materials.3 Quantum dots absorb light from wavelengths shorter then their absorbance edge and then emit light at their luminescence peak wavelength. For example, commercially available gallium ni ...
Fluorescence of coumarins and xanthenes after two
... Two-photon absorption is of interest in spectroscopy because two-photon transitions are governed by different selection rules than one-photon absorption transitions.8 Therefore transitions between singlet states can be excited by two-photon absorption, but they are forbidden for one-photon absorptio ...
... Two-photon absorption is of interest in spectroscopy because two-photon transitions are governed by different selection rules than one-photon absorption transitions.8 Therefore transitions between singlet states can be excited by two-photon absorption, but they are forbidden for one-photon absorptio ...
morphological analysis of chromatophores in the skin of trout
... vertebrates like fishes, amphibians, and reptiles (2, 9, 11). The main function of fish chromatophores is protection of the body against ultraviolet radiation. Skin colours of fish are generated as a result of absorption of light rays by pigmentary substances contained in dendritic melanophores, xan ...
... vertebrates like fishes, amphibians, and reptiles (2, 9, 11). The main function of fish chromatophores is protection of the body against ultraviolet radiation. Skin colours of fish are generated as a result of absorption of light rays by pigmentary substances contained in dendritic melanophores, xan ...
UV/Vis Light Absorption in Clinical Chemistry
... UV/VIS spectra are rather featureless at room temperature, which is why the technique is primarily used for quantitative analysis rather than for sample identification purposes. A broad ultraviolet (UV) spectrum is composed of many separate electronic transitions which, at room temperature, become ‘ ...
... UV/VIS spectra are rather featureless at room temperature, which is why the technique is primarily used for quantitative analysis rather than for sample identification purposes. A broad ultraviolet (UV) spectrum is composed of many separate electronic transitions which, at room temperature, become ‘ ...
Lecture 10: Photosynthesis
... All pigments except chlorophyll a are called as accessory pigments or antenna pigments. The light energy absorbed by accessory pigments is transferred to chlorophyll a molecule. The transfer of light energy from accessory pigments to chlorophyll a is called as resonance or Forster transfer and takes ...
... All pigments except chlorophyll a are called as accessory pigments or antenna pigments. The light energy absorbed by accessory pigments is transferred to chlorophyll a molecule. The transfer of light energy from accessory pigments to chlorophyll a is called as resonance or Forster transfer and takes ...
chapter 5: effect of the optical properties of the epidermis on laser
... The effectiveness of lasers in photodynamic treatment (PDT) of cancerous tumours has been described widely (Sharman WM, 1999), (Brown SB, 2004), (Wilson BC, 2008), (Sekkat N, 2012). In the initial testing phase of a potential treatment, tests are done in biochemical laboratories with single cell lay ...
... The effectiveness of lasers in photodynamic treatment (PDT) of cancerous tumours has been described widely (Sharman WM, 1999), (Brown SB, 2004), (Wilson BC, 2008), (Sekkat N, 2012). In the initial testing phase of a potential treatment, tests are done in biochemical laboratories with single cell lay ...
No Slide Title
... • Permits generation of ROS with spatial selectivity • Uses longer wavelengths to excite ultraviolet-absorbing chromophores • Minimizes scatter to permit deeper tissue penetration • Potentially permits greater chromophore specificity • Allows for the assessment of the whole tissue response to damage ...
... • Permits generation of ROS with spatial selectivity • Uses longer wavelengths to excite ultraviolet-absorbing chromophores • Minimizes scatter to permit deeper tissue penetration • Potentially permits greater chromophore specificity • Allows for the assessment of the whole tissue response to damage ...
Eradication of Propionibacterium acnes by its endogenic porphyrins
... bacteria [16,18,21,22]. A new method for photosensitizing cells is by enhancing endogenous porphyrin production with N-aminolevulinic acid (ALA), which is a naturally occurring metabolite in the synthesis pathway of cellular heme production [23]. In bacteria, addition of ALA may also induce porphyri ...
... bacteria [16,18,21,22]. A new method for photosensitizing cells is by enhancing endogenous porphyrin production with N-aminolevulinic acid (ALA), which is a naturally occurring metabolite in the synthesis pathway of cellular heme production [23]. In bacteria, addition of ALA may also induce porphyri ...
Cls 332 lab 2
... which is the emission of photons from electronically excited states. Fluorescence occurs when the electron is transferred from a lower energy state into an "excited" higher energy state. The electron will remain in this state for 10⁻⁸ sec. then the electron returns to the lower energy state and it r ...
... which is the emission of photons from electronically excited states. Fluorescence occurs when the electron is transferred from a lower energy state into an "excited" higher energy state. The electron will remain in this state for 10⁻⁸ sec. then the electron returns to the lower energy state and it r ...
Absorption & Emission
... UV-Visible Spectroscopy • Ultraviolet-visible spectroscopy involves the absorption of ultraviolet/visible light by a molecule causing the promotion of an electron from a ground electronic state to an excited electronic state. • Ultraviolet/Visible light: wavelengths (l) between 190 and 800 nm ...
... UV-Visible Spectroscopy • Ultraviolet-visible spectroscopy involves the absorption of ultraviolet/visible light by a molecule causing the promotion of an electron from a ground electronic state to an excited electronic state. • Ultraviolet/Visible light: wavelengths (l) between 190 and 800 nm ...
Excited State Processes and Application to Lasers The technology
... Figure 2 Example Jablonski diagram shown the processes of internal conversion (IC), intersystem crossing (ISC), S1 S0 fluorescence and T1 S0 phosphorescence. Stimulated emission is only practical from a singlet state. The ideal laser material has a large absorption, and therefore stimulated emis ...
... Figure 2 Example Jablonski diagram shown the processes of internal conversion (IC), intersystem crossing (ISC), S1 S0 fluorescence and T1 S0 phosphorescence. Stimulated emission is only practical from a singlet state. The ideal laser material has a large absorption, and therefore stimulated emis ...
PowerPoint 簡報
... UV-Visible Spectroscopy • Ultraviolet-visible spectroscopy involves the absorption of ultraviolet/visible light by a molecule causing the promotion of an electron from a ground electronic state to an excited electronic state. • Ultraviolet/Visible light: wavelengths (l) between 190 and 800 nm ...
... UV-Visible Spectroscopy • Ultraviolet-visible spectroscopy involves the absorption of ultraviolet/visible light by a molecule causing the promotion of an electron from a ground electronic state to an excited electronic state. • Ultraviolet/Visible light: wavelengths (l) between 190 and 800 nm ...
B) Alga`s photosynthetic pigments absorb photons at specific
... A. Either of the two cells could be used because both are capable of absorbing light and producing oxygen in photosynthesis. B. Either of the two cells could be used because they both contain the same number of chloroplasts. C. The top cell should be used because the arrangement of chloroplasts allo ...
... A. Either of the two cells could be used because both are capable of absorbing light and producing oxygen in photosynthesis. B. Either of the two cells could be used because they both contain the same number of chloroplasts. C. The top cell should be used because the arrangement of chloroplasts allo ...
Surface Enhanced Fluorescence
... • Quantum Dots are highly photostable. • Light absorbed by metal --> fluorophore • Potential Effects of fluorophore in Nanoshell: – Photostability (Protection from oxygen) – Higher radiative decay rates and higher quantum yields – Emission is 2-fold narrower – Shorter lifetime --> less time for phot ...
... • Quantum Dots are highly photostable. • Light absorbed by metal --> fluorophore • Potential Effects of fluorophore in Nanoshell: – Photostability (Protection from oxygen) – Higher radiative decay rates and higher quantum yields – Emission is 2-fold narrower – Shorter lifetime --> less time for phot ...
Fluorescence Spectroscopy
... • Mirror-image rule typically applies when only S0 Æ S1 excitation takes place g rule are observed when S0 Æ • Deviations from the mirror-image S2 or transitions to even higher excited states also take place ...
... • Mirror-image rule typically applies when only S0 Æ S1 excitation takes place g rule are observed when S0 Æ • Deviations from the mirror-image S2 or transitions to even higher excited states also take place ...
Introduction to Fluorescence Spectroscopies I. Theory
... suggested by A. Jablonski (1935) (see Fig. 1). The ground, first, and second electronic states are depicted by S0, S1, S2, …, respectively. The letter S (in this context) indicates a singlet excited state, in which the electrons remain paired (total spin = 0) during the excitation. In a triplet sta ...
... suggested by A. Jablonski (1935) (see Fig. 1). The ground, first, and second electronic states are depicted by S0, S1, S2, …, respectively. The letter S (in this context) indicates a singlet excited state, in which the electrons remain paired (total spin = 0) during the excitation. In a triplet sta ...
Excited States, Lasers and Non-Linear Optics
... • A radiative decay process involves emission of a photon. • Non-radiative decay involves the transfer of excess energy into vibration, rotation, and translation of surrounding molecules. The result is to heat the surroundings. - Vibrational relaxation - Internal conversion processes ...
... • A radiative decay process involves emission of a photon. • Non-radiative decay involves the transfer of excess energy into vibration, rotation, and translation of surrounding molecules. The result is to heat the surroundings. - Vibrational relaxation - Internal conversion processes ...
Problem Set 1 (due 2/21/06)
... 2. How do you collect a fluorescence emission spectrum? A fluorescence excitation spectrum? An absorption spectrum? Which two most closely resemble each other? A fluorescence emission spectrum is collected by illuminating the sample with a single wavelength and collecting a scan of the intensities o ...
... 2. How do you collect a fluorescence emission spectrum? A fluorescence excitation spectrum? An absorption spectrum? Which two most closely resemble each other? A fluorescence emission spectrum is collected by illuminating the sample with a single wavelength and collecting a scan of the intensities o ...
Photodynamic therapy
Photodynamic therapy (PDT), sometimes called photochemotherapy, is a form of phototherapy using nontoxic light-sensitive compounds that are exposed selectively to light, whereupon they become toxic to targeted malignant and other diseased cells (phototoxicity). PDT has proven ability to kill microbial cells, including bacteria, fungi and viruses. PDT is popularly used in treating acne. It is used clinically to treat a wide range of medical conditions, including wet age-related macular degeneration and malignant cancers, and is recognised as a treatment strategy which is both minimally invasive and minimally toxic.Most modern PDT applications involve three key components: a photosensitizer, a light source and tissue oxygen. The combination of these three components leads to the chemical destruction of any tissues which have both selectively taken up the photosensitizer and have been locally exposed to light. The wavelength of the light source needs to be appropriate for exciting the photosensitizer to produce reactive oxygen species. These reactive oxygen species generated through PDT are free radicals (Type I PDT) generated through electron abstraction or transfer from a substrate molecule and highly reactive state of oxygen known as singlet oxygen (Type II PDT). In understanding the mechanism of PDT it is important to distinguish it from other light-based and laser therapies such as laser wound healing and rejuvenation, or intense pulsed light hair removal, which do not require a photosensitizer.