Chen Muwu felt that the aging old Prague was like that annoying Tang Monk who kept chanting the tightening curse.
Because until he turned around and left his laboratory, he was still chattering.
After sending Old Prague away, Oppenheimer took out a reply letter from the bag he carried with him and handed it to Chen Muwu.
The person who wrote this letter was, of course, Dr. Chen's number one fan at Leiden University, Yoshio Nishina, who was determined to devote his life to the cause of low-temperature physics.
Yoshio Nishina's response to the letter was quite formal, reflecting his full respect for Chen Muwu, who had helped him a lot in physics.
He also reported to Chen Muwu that his research on metallic thallium superconductivity at Leiden University was not going well.
But after reading some encouragement from Dr. Chen, I will definitely persevere and never give up until I explore the superconducting properties of thallium metal!
After reading this reply, Chen Muwu realized how half-baked the letter he sent him was.
To write a letter in the tone of a Heisei waste is somewhat disrespectful to the Meiji man.
It is estimated that Yoshio Nishina felt awkward when he read the letter at the time, but he did not say it in his reply out of respect for Chen Muwu.
In addition to this reply, Oppenheimer also sent a message from Kitham, director of the Low Temperature Physics Laboratory at Leiden University.
He could understand why Chen Muwu bought liquid hydrogen.
Although the liquefaction temperature of hydrogen is a few Kelvin higher than the lowest gas, helium, the refrigeration effect is not as good as liquid helium.
But because hydrogen is easier to prepare, unlike helium, it basically only exists in the air.
Therefore, the price of liquid hydrogen is correspondingly much lower than the price of liquid helium.
It's just that he doesn't buy liquid helium but liquid hydrogen. Why should he buy liquid nitrogen that has a boiling point several dozen kelvins higher than liquid hydrogen while buying liquid hydrogen?
You know, the metal element with the highest superconducting critical temperature found so far is only 7.2 Calvin of lead.
Liquid nitrogen at more than 70 kelvin is completely useless for superconducting experiments!
And if liquid nitrogen is just used as a cooling medium, then liquid air, which is only a few Kelvin higher than liquid nitrogen, should be a more affordable choice.
I just heard Old Prague say that Chen Muwu was defrauded of a large sum of money by the Dutch, and Oppenheimer has always been worried about it.
So at the end of his narration, he did not forget to complain: "These Dutch people are really hypocritical. They obviously made a lot of money from this transaction, but they still pretend to think about us and save us money." I believe that Mr. Chen, you have your reasons for buying liquid nitrogen instead of liquid air. It’s just that they are stupid and can’t figure it out.”
Can't figure it out? Just don’t understand!
I just miss the good times when I secretly ate bananas frozen in liquid nitrogen in the modern physics laboratory, and I want to relive it, can’t I?
In fact, Chen Muwu didn't have any sense. He didn't even think about using liquid nitrogen. This was just a cover-up method.
If it was not Oppenheimer who was sent to buy equipment this time, but Yoshio Nishina, he would even want to buy some more liquid oxygen.
If you don't buy these deceptive things, but just buy liquid hydrogen in large quantities, and after Chen Muwu distills deuterium from the liquid hydrogen, Kitham will probably be more suspicious of whether this Dr. Chen has long known about the existence of deuterium, an isotope of hydrogen. Already?
Otherwise, why would he just buy so much liquid hydrogen by name?
"Okay Robert, don't think so much. Next, we should do the experiment seriously. I only have one request for you, quit smoking completely. Every time you come to the laboratory, don't talk about cigarettes, even You can’t bring in even a single match.”
The David Faraday Laboratory is a very metaphysical place, and Chen Muwu has to be careful here.
Nearly forty years ago, in 1886, Sir Dewar already had a criminal record.
Here he once mixed liquid oxygen and liquid ethylene, causing a big explosion that shocked London directly in the laboratory.
Fortunately, Sir Dewar was lucky enough to escape the disaster, otherwise he would never have lived to successfully liquefy hydrogen.
The power of liquid hydrogen is several times greater than that of liquid ethylene.
If we say that conducting experiments in an environment with radioactive radiation like that of Cavendish Laboratory and radium researchers in Paris, France, is a kind of chronic suicide.
Then lighting a fire and smoking in the Davy-Faraday Laboratory where liquid hydrogen exists is definitely a shortcut to instantly transcend yourself and ascend to heaven.
Moreover, the spirit and body were both lifted into the sky. The Long March 5 rocket that launched the space station was filled with liquid hydrogen!
If liquid hydrogen exploded in the Davy Faraday Laboratory, maybe the first country to master the technology of sending people into space would not be the Soviet Union but the United Kingdom.
The first person to enter space was not Yuri Gagarin, but Chen Muwu.
Of course, this does not change the fact that Soviet Union was the first country to send a living person into space.
It does not change the fact that Gagarin was the first living person to enter space.
"Teacher Chen, you don't need to tell me this, I understand it! When I left Leiden University, they made it clear to me, and I didn't dare to neglect it at all."
Oppenheimer may have been a smoker, but when he entered the Cavendish Laboratory and learned that Chen Muwu did not smoke and hated the smell of tobacco, he had slowly reduced the frequency and frequency of smoking.
Even if Chen Muwu doesn't say anything this time, he still has strong self-control to consciously comply with quitting smoking.
After "No Smoking" signs were posted outside the laboratory door and in the corridor, Chen Muwu and Oppenheimer gently lifted the unpacked refrigeration equipment from the box to the specially designed An experimental platform built by him.
After careful inspection, Chen Muwu found that what Old Prague said was correct or not.
This machine does have the Linde nameplate on it, but it has been modified by the staff of the Low Temperature Physics Laboratory of Leiden University.
If someone charges him a modification fee, it shouldn't be considered a middleman making a difference.
The malice in Old Prague's words was probably due to his prejudice as an Englishman against the Dutch who had been at war with them for hundreds of years.
According to the operating procedures that Chen Muwu learned when he visited Leiden, and the operating instructions that came with the machine, he assembled the machine.
Then add refrigerant and start the power supply. Through layer-by-layer cooling, the temperature can indeed be reduced a lot.
There is no problem at all if you want to reach an extremely low temperature environment of about one kelvin.
But Chen Muwu doesn't need to lower the temperature so low now.
He now only needs to transfer the liquid hydrogen into the experimental container, and then maintain the ambient temperature of the experiment at about 20 Kelvin to 22 Kelvin.
This temperature range can keep deuterium and deuterated hydrogen with higher boiling points in a liquid state, while liquid hydrogen will turn into gas and evaporate as it reaches its boiling point.
Maintaining this temperature and repeating the evaporation step will gradually reduce the liquid hydrogen content in the liquid.
Correspondingly, the contents of liquid deuterium (D) and liquid deuterated hydrogen (HD) also gradually increase.
When the concentration of deuterium increases to a certain level, the spectrum of deuterium can be observed in the spectral lines of this mixed gas.
Since the deuterium atom has one more neutron than the hydrogen atom, a simple calculation using the formula of the atomic spectrum can show that the Balmer spectral line of the deuterium atom will be blue-shifted based on the spectral line of the hydrogen atom, and the change in wavelength is, Between 0.1 nanometer and 0.2 nanometer.
Although the amount of this blue shift is very small, it is not a problem at all when observed in a spectrometer.
To put it bluntly, in addition to maintaining a low temperature environment and being careful to avoid explosions, the experiment of separating deuterium gas from liquid hydrogen is a process of slow work and meticulous work.
Although there is only one deuterium atom for every seven thousand hydrogen atoms, as long as you are patient, you can get the final result you want.
Of course Chen Muwu knew what he wanted, but Oppenheimer didn't.
From his perspective, Teacher Chen seemed to be squandering the liquid gas he had bought from the Netherlands after all the hard work.
No matter how much Oppenheimer trusted Chen Muwu unconditionally, he could not turn a blind eye to the teacher's "wasteful" behavior.
Finally, he couldn't help but ask: "Teacher, when you were in Leiden, didn't you say you were going to do low-temperature physics experiments to study the superconducting properties of metals?
"But now I don't quite understand what you are doing. If the small amount of liquid hydrogen is evaporated, what else can we use as a medium to obtain a lower temperature?"
At this point, Chen Muwu could only tell the truth to his good student: "Robert, while you were in the Netherlands, I suddenly had a new idea.
"It does look beautiful when metal suddenly loses its superconducting property of resistance at extremely low temperatures. But I think it's a little less interesting than my new idea.
"So I plan to change my research direction, but please don't worry, these instruments and liquid gases you brought back from the Netherlands are very important to me. Your journey is not in vain."
The last paragraph was added temporarily by Chen Muwu because he saw that Oppenheimer's mood was declining rapidly.
Anyone who travels across mountains and rivers with a bunch of such dangerous things, only to be suddenly told that they are of no use as soon as they return to the laboratory, will not be happy.
For the first time in the past year, Oppenheimer could not accept Chen Muwu's statement.
He decided to break the casserole and ask: "So, Teacher Chen, what research are you doing now?"
"Have you ever heard of isotopes? Since Blackett and I discovered oxygen-17, the first isotope of oxygen, at the Cavendish Laboratory at the end of the year before last, there has been only one isotope of an element left in the world. It has not been discovered, and this element is the first one on the periodic table, hydrogen.”
"So, are you looking for isotopes of hydrogen? That's what this low-temperature distillation experiment is doing now?"
“That’s right, while I was waiting for you to come back from the Netherlands, I once conducted a simple calculation using the Debye model, and the result was that the boiling point of molecules composed of heavy isotopes should be slightly higher than that of light isotopes.
“If it were another element, I would also consider whether its isotope should be heavier or lighter compared to its original form.
“But for hydrogen, there is no such worry at all.
"Because if one atomic mass unit is subtracted from the hydrogen atom, nothing will be left. Therefore, if there are isotopes of hydrogen, its mass will definitely be heavier than that of hydrogen, and its boiling point will be higher accordingly."
"I understand, you are planning to use repeated distillation to see if there will still be some liquid left in the end, right? If it is left, it will indicate the presence of hydrogen isotopes?"
"It doesn't have to be so troublesome. You just need to occasionally take some out of the remaining liquid and observe its spectrum. Maybe you can find the presence of heavy hydrogen through new spectral lines.
"I think Harvard University must have taught you how to do the experiment of observing the spectrum of hydrogen atoms, right?"
Chen Muwu felt that he could not send Oppenheimer to complete the experiment alone like Blackett did, nor could he be allowed to do nothing like a hands-off shopkeeper.
It is still necessary to increase the intensity of this good student so that he can also increase his sense of participation in the experiment.
Lest this prick head have nothing to do all day long and hang around him asking questions.
Maybe one day, when I'm not paying attention while observing the experimental equipment, I will be tricked into saying something I shouldn't say.
The provoking method really works.
"Mr. Chen, you are really good at joking. I admit that my hands-on ability is a bit poor. If it weren't for you, I would never have entered the Cavendish Laboratory. But if I don't know how to use a spectrometer to observe spectra, I can't I have no shame in staying with you anymore.
"But are you really sure that this heavy hydrogen isotope can be found in liquid hydrogen? And even if heavy hydrogen is found, what use can it be?"
What use can it be?
It doesn't seem to be of much use, it just helps you win a mere Nobel Prize in Chemistry.
Old Mo, Old Mo, why don’t you understand the good intentions of my teacher?
Moreover, when cyclotrons are available in the future, deuterons can be used to bombard molybdenum targets to obtain the extremely mysterious element 43 that chemists have been searching for for more than 80 years.
Uranium element 92 is already on the periodic table, but it doesn't matter that there is always an empty spot in the middle, right?
Oppenheimer still set up a spectrometer in the laboratory as usual, ready to observe the spectrum of the product.
Chen Muwu was still staring at the evaporation process of liquid hydrogen in the instrument as usual.
He suddenly felt like the Supreme Lord standing by the alchemy furnace, and Oppenheimer was the little Taoist boy fanning himself in the Tushita Palace.
It's a pity that the furnace is not filled with Bimawen, which can reach heaven and earth, but hydrogen.
I originally spent a long time writing about May 30 today, but after much deliberation, in order for this book to live longer, I decided not to write it. I could only let the author and the protagonist selectively forget about it, so I deleted it. It took half a day to make changes.
(End of chapter)
