What is the luminescence principle of fluorescent materials, and what is the luminescence principle

This can be explained by the knowledge of the atomic part of the physics elective book in the third year of high school.

Electrons outside the atoms of matter can have multiple energy levels, with the lowest energy being the ground state. When the energy of a photon is equal to the energy difference between the two energy levels, the electron will absorb the energy of the photon and move more and more to the excited state. When the electrons are unstable in the excited state, they migrate back.

When there are multiple energy levels between the excited state and the ground state, different photons can be emitted due to the different energy levels returned, and when there are photons corresponding to the photon energy of visible light, visible light is emitted. But the photon energy of the visible light emitted will certainly not be greater than the photon energy absorbed.

The principle that a substance fluoresces when irradiated by ultraviolet light:

The energy of the photon of ultraviolet light is greater than that of visible light. When the fluorescent substance is irradiated by ultraviolet light, its electrons will absorb the photons of ultraviolet rays and move to the excited state, when he transitions to the ground state, because there are other energy levels between the excited state and the ground state, the photon energy released at this time is lower than the energy of ultraviolet light, and just within the range of visible light, so the fluorescent substance emits visible light, that is, the so-called fluorescence.

The white light emitted by common fluorescent lamps is actually emitted by a variety of fluorescent substances, each emitting a color of light, combined in a certain proportion, it will be combined into the white light we see (white light is polychromatic light).

I'm not typing fast, and I hope forgive me for not being detailed enough in some places.

Fluorescent materials are divided into phosphorescent type, reflected light type, and two-agent reaction type. These three are the most common three, and they have different luminescence principles.

1. Phosphorescent: To put it simply, it is a process of rapid absorption and slow release.

2. Reflected light type: It is composed of a substance with a large surface secretness and strong molecular polishing, which is a kind of parallel diffuse reflection to put it bluntly.

It's the same principle as a bicycle taillight.

3. Two-dose reaction type: It is composed of two chemical agents, and a chemical reaction will occur when the two doses meet.

It shines from the production.

Introduction to Fluorescent Materials:

Fluorescent materials are made of metal (zinc, chromium) sulfides.

or rare earth oxides are calcined with trace active agents. Colorless or light white, is in ultraviolet light.

200 400nm), depending on the type and content of metals and activators in the pigment, it presents a variety of colors of visible light.

400～800nm)。

Characteristics: With the progress of science and technology, people have more and more research on fluorescence, and the application range of fluorescent substances is becoming more and more extensive. Fluorescent substances are used as dyes.

In addition, it has been widely used in organic pigments, optical brighteners, photooxidants, coatings, chemical and biochemical analysis, solar traps, anti-counterfeiting markings, drug tracers and lasers.

Glow sticksThe principle of luminescence isPeroxideIt reacts with ester compounds and transfers the energy after the reaction to fluorescenceDyes, which is then fluoresced by the dye.

In 2018, a glass tube interlayer was usually placed in the common glow sticks on the market, and the peroxide and ester compounds were isolated inside and outside, and the two compounds reacted to make the fluorescent dye glow.

Luminescence time. The duration of the glow stick is inversely proportional to the ambient temperature (i.e., the higher the ambient temperature, the shorter the glow time of the glow stick) and inversely proportional to the initial brightness of the glow stick (i.e., the brighter the glow stick is when it is just folded, the shorter the light emitting time).

According to these characteristics of the glow stick, we can inhibit the chemical reaction of the two liquids in the glow stick by placing the glow stick in a low temperature environment (such as refrigerator and freezer).

Remove and continue to use.

Principle of fluorescence generation:

When light hits certain atoms, the energy of the light causes some electrons around the nucleus to jump from the original orbital to the higher energy orbital, that is, from the ground state to the first excited singlet state or the second excited singlet state.

The first excitation singlet or the second excitation singlet is unstable, so it will return to the ground state, and when the electrons return to the ground state from the first excited singlet, the energy will be released in the form of light, so fluorescence is produced.

In addition, there are some substances that can still emit light for a long time after the incident light is removed, and this phenomenon is called afterglow. In daily life, people usually refer to all kinds of faint light as fluorescence in a broad sense, without carefully investigating and distinguishing their luminescence principles.

After the gaseous free atom absorbs the characteristic radiation of the light source, the outer electrons of the atom transition to a higher energy level, and then transition back to the ground state or a lower energy level, and at the same time emit the same or different emission from the original excitation wavelength, which is atomic fluorescence. Atomic fluorescence is photoluminescence and secondary luminescence. When the excitation light source stops irradiating, the re-emission process stops immediately.

When fluorescent material is used as a custom t-shirt material, it is a raw material in the textile industry. But in addition to the textile industry, fluorescent materials are also widely used in many other fields. In what ways do fluorescent materials have a volatile effect? Apply to the location of the identity.

Fluorescent materials are used in electrical switches, remote control boards, wall switches, plugs, sockets, locks, portable flashlights, door handles, handrails, fire extinguishing equipment, fire alarms, life-saving appliances, etc., which can indicate their location and facilitate their use.

Fluorescent logo. Fluorescent materials are used for signals, precautions writing, emergency evacuation channels, subway stations, underground passages, civil air defense projects, karaoke halls, song and dance halls, screening halls, supermarkets, hospitals, railway stations, airports, docks, shelters, etc.

Fluorescent building materials.

Fluorescent materials are applied to building walls, tiles, elevator inner surfaces, bridges, roads such as street signs, road studs, barricades, ports, outdoor advertising, etc. Others: such as handicrafts:

amber, crystal sand, glass, paintings; Toys: plastic toys, puzzles, building blocks; Clothing: shoes, hats, gloves, overalls, T-shirts, cultural shirts, helmets, printed clothing; Wall calendars, fishing tackle, etc.

Summary. The luminescence principle of fluorescence is based on the principle of electronic structure and energy level transitions of matter.

The luminescence principle of fluorescence is based on the principle of electronic structure and energy level transitions of matter.

The luminescence principle of fluorescence can be explained by a simple model. In this model, the electrons in the atoms or molecules of a substance are at different energy levels. When matter is stimulated by a lack of external energy, electrons jump from a lower energy level to a higher energy level, a process known as excitation.

When an electron jumps back from a higher energy level back to a lower energy level, energy is released, a process known as emission. In fluorescence, when the electrophobic acacia jumps from a higher energy level back to a lower energy level, it releases photons, which are fluorescent luminescence.

The principle of phosphor luminescence is as follows:

Phosphors (commonly known as luminous powders) are usually divided into two categories: photoinduced energy storage luminous powder and radioactive luminous powder. Photoluminous energy storage luminous powder is a phosphor that stores light energy after being irradiated by natural light, daylight light, ultraviolet light, etc., and then slowly releases it in a fluorescent way after stopping light irradiation, so it can still see the luminescence at night or in a dark place, and it lasts for several hours to more than ten hours. Radioactive luminous insect finger cluster powder is mixed with radioactive substances in phosphor, and the light emitted by radioactive substances is used to excite phosphor luminescence.

Phosphor applications are as follows:

1. Make a weak illumination light source

People use the characteristics of luminous powder to shine for a long time in actual life, make a weak lighting source, have a special use in the military department, and apply this material to various switch signs on aviation instruments, clocks, windows, machines, door handles, etc., and can also be pressed into various symbols, components, supplies (such as power switches, sockets, fishing hooks, etc.) together with various translucent plastics. These light-emitting parts continue to glow at night or when they get up after an unexpected power outage or lightning, allowing people to distinguish the direction of their surroundings and bring convenience to their work and life. The ultrafine particles of the luminous material tare wheel are incorporated into the textile to make the color more vivid, and children can wear luminous textiles to reduce traffic accidents.

2. Luminous material:

Luminous materials at home and abroad are mainly made of ZNS (zinc sulfide), SRS (strontium sulfide) and Cas (calcium sulfide), emitting green and yellow light. However, SRS and Cas materials are easy to deliquescent, which brings difficulties to a wide range of applications. Therefore, the market is mainly based on ZNS luminous materials.

However, its afterglow time is only 1 3 hours, and it is easy to deteriorate and blacken in strong light (such as sunlight), ultraviolet light and humid air, so its application in many fields is limited. Although the ZNS luminous powder co-activated with drill and copper has a long afterglow time, it has an infrared quenching phenomenon, and the afterglow is quickly extinguished under the irradiation of electric lights (including more red light). <>