The difference between household lighting tubes and ultraviolet lamps
1. Fluorescent lamp structure and function
There is a filament at both ends of the fluorescent lamp. The tube is filled with traces of argon and thin mercury vapor. The inner wall of the tube is coated with fluorescent powder. The gas between the two filaments emits ultraviolet rays when conducting electricity, making the fluorescent powder emit soft Visible light.
2. Working characteristics of fluorescent lamp
When the lamp starts to ignite, a high voltage is required, and only a small current is allowed to pass during normal lighting. At this time, the voltage at both ends of the lamp is lower than the power supply voltage.
When electrons are excited, atoms will release visible photons. If you already know how atoms work, then you also know that electrons are negatively charged particles that walk around the nucleus. The electrons of an atom have different levels of energy, mainly depending on several factors, including their speed and the distance from the nucleus.
Different energy levels of electrons occupy different orbital functions and orbitals. Generally speaking, electrons with high energy are farther away from the nucleus. When an atom gains or loses energy, electrons move between the low and high orbits. When something transfers energy to the atom-take heat as an example-the electron can be temporarily propelled to a higher orbit (away from the nucleus).
The electron only stays in this orbital position for a very short time: it is receded back to the nucleus almost immediately, reaching its original orbit. At this time, the electron emits additional energy in the form of photons. The wavelength of light emission depends on how much energy is released, which also depends on the orbital position of the electron. Therefore, different types of atoms will release different types of visible photons. In other words, the color of light is determined by the type of excited atoms. This is almost the basic working mechanism of all light sources. The main difference between these light sources is the process of exciting the atoms.
In the incandescent light source, the atoms are excited by heating; in the lamp tube, the atoms are excited by chemical reactions. The central element of a fluorescent lamp is its sealed glass tube. This tube contains a small amount of mercury and inert gas, usually argon inert gas element, this inert gas must be kept at very low pressure. The tube also contains fluorescent powder, and a layer of fluorescent powder is separately coated in the glass tube. There is an electrode at each end of the glass tube, which is connected to the current.
When the inert gas in the tube is ionized under high pressure, a gas conduction current is formed, and the moving gas ions continuously give energy to the mercury atom during the collision with the mercury atom, so that the total energy of the extranuclear electrons of the mercury atom From the low orbit to the high orbit, the extranuclear electrons of the mercury atom will spontaneously transition from the high orbit to the low orbit (or ground state) due to their higher energy, releasing energy in the form of photons. At the same time, due to the mercury atom, Most of the atomic characteristic lines are concentrated in the ultraviolet region. It can be seen that most of the photons released by mercury atoms are in the ultraviolet region. These high-energy photons (ultraviolet rays) produce white light between the collisions with the phosphor.
3. The sterilization principle of ultraviolet germicidal lamp
The range of visible light is between 400 nanometers and 780 nanometers. The wavelength of ultraviolet light is shorter than that of visible light, between 100 nanometers and 400 nanometers. Ultraviolet light is divided into three areas:
1, UVA: 315nm-400nm
2, UVB: 280nm-315nm
3, UVC: 100nm-280nm
UVC band light has the ability of broad-spectrum sterilization and disinfection, it can kill bacteria, viruses and various microorganisms, and can make it impossible to reproduce. Ultraviolet sterilization is a purely physical method of disinfection. For the processed objects, no other substances are added or left. Compared with the disinfection method of chemical reagents, it is more environmentally friendly and safer. At the same time, because ultraviolet rays have a bactericidal effect on most viruses and bacteria, it is also widely used in the field of water and air disinfection.