Look at the electrons you see-

Many major breakthroughs in the history of scientific and technological development,

It is closely related to the improvement of human understanding of the microscopic material world.

With the rapid development of science and technology,

We are entering a smaller and smaller microscopic world!

Through optical microscope, electron microscope,

Cryogenic electron microscopes and other equipment,

People have improved the spatial resolution to

Ayae, close to the theoretical limit.

When you enter Yael, you can clearly see the arrangement of atoms!

However, the understanding and description of the material world

In order to understand its essential characteristics more deeply, it is necessary to measure its movement changes in time series and transient state.

So, what can the time resolution be?

0 1 The martial arts in the world are quick and unbreakable.

Due to the persistence effect of human vision, the temporal resolution of eyes is only tens of milliseconds. For objects that move or change within 42 milliseconds, the human eye can hardly distinguish the details clearly. It was not until the appearance of high-speed cameras that it was possible for human beings to observe high-speed moving objects.

High-speed photography uses extremely short exposure time or flash to freeze or "freeze" moving and changing objects in one or a series of moments-frames, and the movement and change of objects in these "moments" can be ignored. When playing back frame by frame, we can observe, study or appreciate the details of the changes.

What is the time scale of the movement of molecules, atoms and electrons in the microscopic world? Why study the time scale of the micro-world? How to study?

02 scientific frontier issues

Science, the top international scientific journal, puts forward 125 most challenging frontier scientific problems, including:

Superconducting magnetic levitation

1, superconductivity, magnetism and other condensed matter physics: all involve the study of micro-dynamics. For example, in superconducting research, knowing the formation time of Cooper pairs is of great significance for understanding the mechanism of high temperature superconductivity, discovering new superconducting materials and understanding transient room temperature superconductivity.

2. Photovoltaic power generation is considered as the main choice for the next generation of clean energy; Its physical process is mainly light-induced surface charge transfer, and the charge transfer process often occurs in femtosecond or even attosecond order. The research on it is helpful to explore photovoltaic materials with higher conversion efficiency.

Information science

3. The application and development of modern electronic technology is based on semiconductor materials, and semiconductors have a long response time because of the small band gap between conduction band and valence band.

Using ultrafast light field to drive the movement of electrons in semiconductor materials has proved that the switching speed of PHz can be achieved, which is more than 10000 times higher than the current CPU clock, which is expected to promote the breakthrough and development of computing technology.

Molecular biology and biomedicine

4. In molecular biology and biomedicine, electron migration in biomolecules such as protein is the key to understand biochemical reaction, drug action mechanism, information and energy transfer, radiation damage, biological variation, microscopic pathogenic mechanism of cancer and physiological function operation.

Understanding these charge transfer processes is helpful to understand the mechanism of biochemical reactions, and finally realize the regulation of the above processes, and then change biological functions to serve mankind.

…

In the quantum mechanics of 100 years, the direct observation of electron motion is almost blank!

Bottleneck scientific problems:

Understanding of microelectronics behavior and dynamics!

Academician Hou Xun, one of the founders of transient optics in China, said: "In physics, chemistry, biology, materials, energy and other disciplines, the most fundamental thing is the movement of electrons. The study of these movements will certainly develop new and original science and technology. "

The difficulty of these problems is that we can't fundamentally understand and reveal the essence of these problems-the law of motion of electrons. And the electron is in the never-ending ultra-high-speed motion, so how can we track and measure it?

03 attosecond laser

The emergence of attosecond laser provides a revolutionary means to solve these challenging scientific problems.

What is a second? Why is attosecond pulse the only tool that can directly measure the transient behavior of electrons?

Different time resolutions correspond to different physical processes and different levels of the world.

The characteristic time of rotation and vibration of small molecules is in the order of picoseconds to femtoseconds, and the characteristic time of electron movement inside atoms is in the order of sub-femtoseconds, that is, attosecond. One second is a very short time unit, 1 one second = 10- 18 seconds. How short is a second?

If "one second" blinks once at the speed of 1 per second, then "one second" can blink hundreds of millions of times in a blink of an eye.

According to Bohr's atomic model, the time for an electron to circle the nucleus is 152 attosecond/circle.

Because the duration of ultrafast laser pulse is shorter than the relaxation time of atoms or molecules, it can be used as a very short "time shutter" to record the transient processes of atoms, molecules and electrons in microscopic substances, thus revealing new physical and chemical phenomena.

00:30

Therefore, an attosecond (as, 10-18 seconds) pulse can be used to "photograph" the instantaneous process of electron motion.

The attosecond laser pulse can cross almost all disciplines, including physics, chemistry, biology, medicine, information, materials and so on. It will surely become a powerful driving force to promote the current scientific and technological progress in the world.

It can be said that attosecond laser is a powerful driving force for the current scientific and technological progress in the world!

04 attosecond laser pulse research, we are in action! Let's have an international brainstorming!

In order to further develop the new technologies and applications of ultrafast physics and attosecond science, from June 65438+1October 16 to June 18, 2022, the "international conference on advanced attosecond laser Soal-2022 scientific opportunities" was co-sponsored by the Institute of Physics of Chinese Academy of Sciences, Xi Institute of Optics and Mechanics of China Academy of Sciences and Songshan Lake Materials Laboratory.

More than 65,438+050 experts from 65,438+02 countries attended the event, and more than 65,438+07,000 people attended the conference by watching the live broadcast. * * * Fifty-eight experts gave keynote speeches, covering physics, chemistry, biology, medicine, information, materials and other disciplines, showing the potential of attosecond pulse as a powerful driving force for the current world scientific and technological progress.

The meeting received extensive support and response from experts in this field at home and abroad. With the rapid development of ultrafast physics and experimental technology, it is possible to detect the multi-body dynamics of electrons and atoms in matter in real time on the order of attosecond femtosecond, which has great application prospects in physics, chemistry, materials, life and other scientific fields. The further development of advanced attosecond laser device combining ultra-fast terahertz and X-ray will provide scientists with ultra-high time resolution to fully understand the micro-dynamic characteristics of matter, thus revealing the structure and dynamic process of matter on attosecond/nanometer time-space scale.

I believe that with the joint efforts of scientists at home and abroad, based on the development of ultrafast and attosecond science, this will open a door for basic research, applied research and industrialization, deepen to a new level and enter a new era.