From Chromic Phenomena: Technological Applications of Colour Chemistry

3.4 High Energy Photoluminescence

Photoluminescence is a term widely applied to the range of phenomena where light emission occurs from a material after energising by photons. In this section of the book the term is specifically applied to the cases where luminescence occurs after the interaction of luminescent materials with narrow band, higher energy ultraviolet radiation, namely in lighting and plasma display panel applications.

3.4.1 Lighting

Luminescent lighting, commonly called fluorescent lighting, has been in regular use for decades since it was first introduced in the 1930s. Its dominance in the illumination of offices, department stores and public spaces arises from the fact that it has a much higher efficiency than incandescent lighting. For instance, a 60 W incandescent light tube generates only 15 lm W ?1 whilst a 40 W luminescent light bulb yields 80 lm W ?1.14

Luminescent light is generated using ultraviolet radiation from a low-pressure mercury discharge, the mercury vapour being present in the noble gas, which fills the tube under low pressure. The emitted radiation consists of 85% at 254 nm and 12% at 185 nm, the remainder being mainly in the visible region. The lamp phosphors, which coat the inside of the tube, convert the 254 nm and 185 nm light into visible light (Figure 3.6). The light emitted must be white light in order to match the ambient natural lighting from the sun. Since the sun is a black body radiator, a terminology has been developed for the lighting...

Copyright The Royal Society of Chemistry 2001 under license agreement with Books24x7

Products & Services
UV Light Systems
UV light systems provide ultraviolet light for identification, tracing, curing, disinfection or processing applications.
Ion Lasers
Ion lasers function by stimulating the emission of radiation between two levels of an ionized gas. They provide moderate to high continuous-wave output of typically 1 mW to 10 W.
Light Emitting Diodes (LED)
Light-emitting diodes (LED) are PN junction devices that give off light radiation when biased in the forward direction. LEDs are used in a wide variety of indication applications.
Ballasts
Ballasts are electrical devices that condition the line voltage (amplitude, amperage and waveform) to operate fluorescent and HID lamps. Basically they serve two functions: to provide the starting kick, and to limit the current to the proper value for a particular lamp.
Lighting Inverters
Lighting inverters provide alternating current (AC) power for indoor, outdoor and emergency lighting, signage, and associated controls.

Topics of Interest

3.5 Fluorescence Fluorescence from organic materials is a very important phenomenon that is exploited in a broad range of application areas. These include their use in the dyeing of synthetic textile...

3.1 Introduction Those phenomena that involve absorption of energy and subsequent emission of light are classified genetically under the term luminescence. This phenomenon is observed when a...

Charles L.Amick Professional Engineer; Lighting Consultant; Fellow, Illuminating Engineering Society of North America (IESNA); Lighting Certified, National Council on Qualifications for the Lighting...

Hugh King, Thorn Lighting 25.1 Lighting Theory 25.1.1 The Nature of Light Light is a form of electromagnetic radiation similar in nature and behaviour to radio waves at one end of the frequency...

3.2 Luminescent Pigments As stated above, there is no intention to provide any detailed discussions of the theory of luminescent phenomena; however, a basic understanding is essential. A simplified...

Product Announcements
Heraeus Noblelight LLC – Optics + Analytics