File:Calcite fluorescing.jpg
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Summary
editDescriptionCalcite fluorescing.jpg |
English: Calcite fluorescing under ultraviolet light. (public display, Sternberg Museum of Natural History, Hays, Kansas, USA)
From museum signage: "Fluorescence occurs at the atomic level. We can think of an atom like a miniature solar system. Electrons orbit the nucleus of the atom like planets orbit the sun. Fluorescence is a two-stage process. First, energy from invisible ultraviolet radiation pushes an electron into a higher orbit around its atomic nucleus. The electron loses much of its newly acquired energy as heat to neighboring atoms, making its higher orbit increasingly unstable. Next, when this "excited" electron falls back to its normal "ground state" orbit, it releases the rest of its acquired energy in a sudden burst. Since the electron already lost some of its acquired energy as heat, the burst emitted is a lower energy, longer wavelength visible light. The emitted light is a specific wavelength of pure color, but very dim. It requires about 10 million individual bursts for the human eye to detect the light. Usually, the entire process occurs in a split second. If it takes several seconds or more for electrons to return to ground state after the UV radiation stops, we see it as an afterglow called phosphorescence. Fewer than 15% of minerals fluoresce. In the minerals that do, only a small percentage of the mineral's atoms generate the fluorescence. We call these activator atoms. Activators vary from mineral to mineral or from locality to locality in the same kind of mineral. The color and strength of fluorescence depends on the kinds of activators present, how they interact with neighboring atoms, and the wavelength of the UV radiation that initiates the process. The processes are complex and highly variable. Commonly, activator atoms occur as chemical impurities replacing the normal atoms in a mineral. (Few pure minerals fluoresce.) Fluorescence may require more than one kind of atom to function as co-activators. In such cases, the second impurity absorbs the UV radiation, transfers the absorbed energy to the primary activator atom, which then emits visible light. Sometimes, the presence of certain secondary impurities can function as quenchers. These impurities absorb energy from otherwise potent activator atoms, preventing them from fluorescing. " |
Date | |
Source | https://www.flickr.com/photos/47445767@N05/32351691636/ |
Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/32351691636. It was reviewed on 19 November 2020 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
19 November 2020
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current | 18:17, 19 November 2020 | 2,304 × 2,088 (3.69 MB) | Ser Amantio di Nicolao (talk | contribs) | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/32351691636/ with UploadWizard |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot D10 |
Exposure time | 3/10 sec (0.3) |
F-number | f/4 |
ISO speed rating | 320 |
Date and time of data generation | 10:42, 13 June 2012 |
Lens focal length | 11.614 mm |
Orientation | Normal |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop CS2 Macintosh |
File change date and time | 14:32, 18 January 2017 |
Y and C positioning | Co-sited |
Exif version | 2.21 |
Date and time of digitizing | 10:42, 13 June 2012 |
Meaning of each component |
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Image compression mode | 3 |
APEX shutter speed | 1.75 |
APEX aperture | 4 |
APEX exposure bias | −0.66666666666667 |
Maximum land aperture | 4 APEX (f/4) |
Metering mode | Pattern |
Flash | Flash did not fire, compulsory flash suppression |
Supported Flashpix version | 1 |
Color space | sRGB |
Focal plane X resolution | 16,460.905349794 |
Focal plane Y resolution | 16,483.516483516 |
Focal plane resolution unit | inches |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Scene capture type | Standard |
Supported Flashpix version | 1 |
Image width | 2,304 px |
Image height | 2,088 px |
Date metadata was last modified | 09:32, 18 January 2017 |
IIM version | 2 |