Funnels are not only effective tools in the kitchen - they can also be used for the effective focus of light. In this case, the funnel is a nano-funnel, that is, many times smaller in size
If we want to avoid spilling liquids when we pour them in our kitchen we will use a funnel. Funnels are not only effective tools in the kitchen - they can also be used for the effective focus of light. In this case, the funnel is a nano-funnel, that is, many times smaller in size.
An international team of scientists from Korea, Germany and the USA has now managed to focus the energy of infrared radiation pulses using a nanofunnel and use this concentrated energy to create highly focused flashes of ultraviolet light. These flashes, which repeat themselves 75 million times every second, lasted for only a few femtoseconds. This new technology will be able to help in the future in the measurements of the movement of electrons and will allow a very high resolution in terms of space and time.
Light is a convertible form - the wavelengths that make it up may change when they come into contact with a material, when both the type of material and its shape are important for frequency conversion. An international team of scientists has now succeeded in changing the light waves using a nanofunnel made of silver metal. The scientists converted laser pulses (femtoseconds = millionths of a billionth of a second) in the infrared spectral range into flashes of light in the extreme ultraviolet (EUV) spectral range. Laser flashes that use this type of radiation are used in the field of physics to study atoms and molecules.
Infra-red radiation can be converted into extreme ultraviolet radiation through a process known as high-harmonic generation, through which the atoms are exposed to a strong electric field originating from the laser pulses of the infra-red radiation. These fields should be at the same level of intensity as the fields that bind together the atoms themselves. Using these fields allows electrons to be moved away from the atoms and accelerated at their full speed back towards the atoms. Their impact on the atoms produces particularly energetic radiation in the spectral range of extreme ultraviolet radiation.
In order to obtain the powerful electric fields required to create this radiation, the research team now used a nanofunnel to focus the electric field of the radiation. Using their new technology, the researchers were able to produce a powerful source of extreme ultraviolet radiation with wavelengths of 20 nanometers. The new radiation source exhibits an extremely high rate of activity that has never been achieved: the flashes of extreme ultraviolet radiation are repeated 75 million times every second.
The core of the experiment was a conical funnel, tiny in size, only a few micrometers long, made of silver metal and filled with xenon gas. The tip of the funnel (the narrow end) was only 100 nanometers thick. The pulses of infrared radiation were directed towards the entrance of the funnel and moved inside it towards the extremely narrow exit. The electromagnetic forces of the radiation caused the electrons to oscillate inside the funnel. The inner walls of the funnel were composed of alternately positively and negatively charged metal areas, thus creating new electromagnetic fields inside the funnel. These fields move towards the narrow tip of the funnel when its cone shape allows these fields to be focused. "The field obtained inside the funnel may be hundreds of times more powerful than the original field of the infrared radiation. It is this powerful amplified field that produces the extreme ultraviolet radiation in the xenon gas," explains Professor Mark Stockman, one of the research scientists.
The nanofunnel has another function - the narrow opening at its exit functions as a "gate" for the wavelengths of light. Not every opening allows the transmission of light through it - if the opening is smaller than half the wavelength of the light, the other side remains dark. The opening of the funnel, which is 100 nanometers in size, did not allow the passage of infrared light with a length of 800 nanometers. On the other hand, the newly created extreme ultraviolet radiation, with a length of only 20 nanometers, did manage to pass through it. "The funnel functions as an efficient wavelength filter: only extreme ultraviolet radiation can pass through its narrow opening," explains one of the research partners.
"In view of their low wavelengths and the short durations of their pulse intervals, extreme ultraviolet radiation flashes are an important means of studying the dynamics of electrons in atoms, molecules and solids," adds one of the researchers. Electrons are extremely fast objects, and in order to examine their movement, the short flashes of radiation from the time scale of the movement itself are needed. "We believe that our new nanofunnel will make it possible to reach a time scale suitable for such research," notes one of the researchers.
The repetition rate of the flashes is also particularly important, for example for the application of extreme ultraviolet radiation in electron spectroscopy on surfaces. The electrons repel each other through coulombic forces. Therefore, it is necessary to limit the experimental conditions so that a single electron is obtained in each laser pulse. "In order to conduct experiments with high resolution in the space axis and the time axis, an extreme ultraviolet radiation source with a high repetition rate is needed," explains the researcher. The innovative combination of laser technology and nanotechnology, inherent in the new nanofunnel, will be able to help in the future to produce videos in which the extremely fast movement of the electron over a surface is visible, with a separation capability that has never been achieved until now.
The news about the study
4 תגובות
The last sentence is wrong, it is possible to excite a single electron from the material, but watching its movement is already excessive,
To observe the movement of an electron without affecting it, you need a particle that affects the electron very little and its mass is low. Here we are talking about energetic photons that created strong electromagnetic fields for short periods of time, it's kind of like trying to watch the movement of a racing boat with a drunk driver with the help of huge sea waves.
I agree that the position of the electron at a given moment can be discovered this way but not its movement, this also contradicts the principle of uncertainty.
Wait, I'll do a degree in physics and I'll be able to understand the article..
So basically it's a very fast stroboscope