Chapter 147 Don’t use experimental equipment as an excuse
Originally Qi Wan thought that it was impossible for Ning Chen to measure a qualified three-dimensional structure diagram for the first time using STM.
When Qi Wan first came into contact with STM, he practiced for several hours before he managed to find the feel of the operation.
"Well, I can swear to the lamp, this is really my first time using STM." Ning Chen said with a smile.
Although Qi Wan was still a little dissatisfied at this time, she thought that Ning Chen did not study physics, and it was indeed unlikely that she had been exposed to STM before.
"Okay, I believe you. Now that you have learned how to operate, let's start the experiment."
......
In the following days, apart from the time for listening to lectures, , Ning Chen comes to Ren Mingshan’s laboratory almost every day to participate in research projects on the surface states of topological insulators.
After a long period of contact, Ning Chen discovered that Qi Wan did have strong professional abilities.
Although Qi Wan looks like a child on the surface, he is very methodical when conducting experiments and has some unique ideas of his own.
This made Ning Chen and Qi Wan very efficient when doing experiments together, and their subject experience increased rapidly.
It’s just that Qi Wan’s character is a bit arrogant, which is in sharp contrast to Song Xiyun’s mature intellectuality.
Ning Chen doesn’t really like girls with this kind of personality, but when it comes to a nineteen-year-old physics genius girl, Ning Chen thinks it’s still acceptable.
On this day, Ren Mingshan came to the laboratory to learn about Ning Chen's situation and the progress of the experiment.
"Ning Chen, how are you feeling recently? Have you adapted to the laboratory environment?"
"Well, I think I'm quite adaptable. Qi Wan taught me a lot, and I can participate in some experiments."
Hearing Ning Chen's words, Qi Wan said:
"Any Teacher, Ning Chen learns things very quickly. If I tell him all the knowledge once, he will remember it all.”
Ren Mingshan also smiled when he heard this:
“Otherwise. How can Ning Chen publish so many papers in Nature at such a young age? Qi Wan, you should learn more from Ning Chen and don’t always think that you are the best.”
Qi Wan pouted slightly, and it could be seen that she was still a little dissatisfied, but she immediately agreed obediently:
"Okay, Teacher Ren, I will learn more from Ning Chen."
< br>After chatting with Ning Chen and Qi Wan for a while, Ren Mingshan checked the progress of their recent experiments.
After reading the various experimental data they recently conducted and the data analysis process, Ren Mingshan frowned slightly, as if there was something that did not satisfy Ren Mingshan.
“Qi Wan, with the surface morphology information of the sample we have obtained now, can we obtain the electronic standing wave of the surface state of a topological insulator?”
Hearing this question, Qi Wan replied in a low voice:
"Teacher Ren, it's not possible yet. Our scanning tunneling microscope has not yet reached such accuracy."
Ning Chen also knew This problem exists, although the scanning tunneling microscope can perform atomic-level imaging of the sample surface in real space.
However, it cannot give information about the material in the reciprocal space, and this problem has not been solved yet.
Ren Mingshan was obviously not satisfied with Qi Wan’s answer and said seriously:
"So, is it a problem with the instrument? The scanning tunneling microscope in our Yanda laboratory is the most advanced in the world. I can't build you a new scanning tunneling microscope just for this subject. Right? "
Qi Wan's face immediately turned ugly after being criticized like this by Ren Mingshan.
"Teacher Ren, I will continue to think of other ways."
Ren Mingshan also knows that Qi Wan is only a nineteen-year-old girl after all, and her own words are not enough to this extent. It's ready.
"Well, this is the correct attitude towards scientific research. Our previous scientific research environment was far less good than it is now, and we have suffered far more hardships than you have, but haven't we survived it all? Yes. There are only so many things available at the moment. Since we can’t change external factors, we can only think of ways from other aspects.”
Qi Wan stopped talking and nodded like garlic, without any refutation of Ren Mingshan's words.
This is the first time Ning Chen has seen Ren Mingshan like this. In class, Ren Mingshan always gives people a very approachable feeling.
But facing his own student Qi Wan, Ren Mingshan was still very strict.
Ning Chen can also understand this situation. Many professors will appear very friendly during class, but the more they treat the students they teach, the more severe they will criticize.
It is very rare for teachers and students to get along like friends like Xu Zhou and Ning Chen.
Ning Chen knew that perhaps a certain amount of criticism would be more conducive to students' growth, but if Ning Chen had a choice, he would still like this way of getting along with Xu Zhou. After Ren Mingshan left, Qi Wan stopped pretending and his face immediately dropped.
Ning Chen can actually understand Qi Wan's current mood. If it were Ning Chen, although he would not act as strongly as Qi Wan, he would definitely not be very happy in his heart. .
Qi Wan didn't speak much throughout the morning, just silently conducting experiments, and all that arrogant arrogance disappeared.
Ning Chen was too lazy to coax Qi Wan, and started thinking about the solution to this problem.
"Actually, what Qi Wan said is correct. With the precision of this scanning tunneling microscope, it is indeed difficult to directly observe the electron standing wave in the surface state of a topological insulator."
But Ning Chen cannot directly move it from the future. A more advanced instrument can only find other ways to solve this problem.
Ning Chen thought about it for a long time. Suddenly, Ning Chen really thought of a plan that he could try.
“If impurities or defects can be introduced on the surface of the sample, maybe we can observe the electron standing wave in the surface state of the topological insulator.”
The reason why Ning Chen thought of this method is Because the introduction of impurities into the sample can lead to elastic scattering of quasiparticles.
In this way, the eigenstates of different wave vectors on the same equal energy surface can be related to each other.
Thinking of this idea, Ning Chen did not rush to try it, but first deduced it on the draft paper.
Ning Chen calculated various data of the incident wave after ejection through various relevant formulas. Finally, based on the wave vector, wavelength, period, momentum and other data of the ejection wave, Ning Chen obtained the possible characteristics of the ejection wave. Standing wave pattern.
After completing the drawing of the standing wave pattern, Ning Chen felt more and more that his idea was feasible.
“In this case, even if the original scanning tunneling microscope is still used, the measurement results will be completely different.”
In excitement, Ning Chen called Qi Wan over.
"Qi Wan, come here."
"What's wrong..."
Qi Wan still looks listless and is criticized every time by Ren Mingshan , Qi Wandu had to recover the next day.
“Look at this.”
Ning Chen didn't bother to explain it carefully to Qi Wan, so he directly handed his draft paper to Qi Wan.
After seeing the draft paper, Qi Wan's expression was indifferent at first, then he frowned, and his brain continued to work.
Qi Wan is not an ordinary student after all. After reading the content on Ning Chen’s draft paper, he quickly understood what Ning Chen wanted to express.
Qi Wan also took out the paper and started calculating by himself. After a few minutes, Qi Wan said excitedly:
"Yes, Ning Chen, your method is feasible! Maybe it's possible. We can really use this broken microscope to measure the electron standing wave in the surface state of a topological insulator! ”
Qi Wan swept away the gloom just now, and a smile began to appear on her baby-fat face again.
But listening to Qi Wan's words, Ning Chen also knew that Qi Wan still held a grudge against Ren Mingshan's criticism just now.
“Didn’t you say before that the price of this microscope was 200,000 yuan? Why is it now a broken microscope?”
“Okay, okay, I’m just venting. Just for a moment. Don’t say so much, let’s verify it quickly.”
The two took a look at the time and found that it was already noon, so they decided to go to the cafeteria to have a meal first, and then come back to continue the experiment.
After all, Ning Chen often loses track of time when doing experiments seriously. If he wants to maintain a long-term and continuous research state, he must still eat well.
Ning Chen and Qi Wan came to the canteen together. They each ordered a bowl of noodles. After a few minutes of eating, they returned to the laboratory to prepare for experiments.
Although the new experimental idea has been determined, there are still many details that need to be finalized for specific implementation.
For example, if impurities are added to the sample, what specific impurities are added and the amount added.
If there is a structural defect, how to construct it, what is the scope of the defect, etc., these are all issues that need to be studied.
(End of this chapter)