Chapter 269

Anti rice chapter, please do not subscribe!!

Anti rice chapter, please do not subscribe!!

Anti rice chapter, please do not subscribe!!

Anti rice chapter, please do not subscribe!!

as everyone knows.

Both the three-dimensional reconstruction of cryoelectron microscope and XRD, that is, X-ray crystal diffraction, are discussed in Angstrom.

That is, 10-10 square meters, that is, 0.1 nm. When it reaches the atomic scale, we can see the covalent bond connection between atoms.

Although the above two technologies are physicochemical technologies, they have been widely used in biological detection in modern life science.

In modern life science, the three schools of materialization and biochemistry are basically inseparable from each other.

The above two technologies are standard crystal detection technologies, especially crystal X-ray diffraction, which have become so mature that even a paper can't find water.

It is still well known.

The crystal has a lattice structure, and the period of the lattice structure belongs to the same order of magnitude as the wavelength of X-ray. Therefore, X-ray diffraction is an interference phenomenon based on the principle of wave superposition.

After X-ray passes through the crystal, the intensity of X-ray increases in the diffraction direction, while the intensity of X-ray decreases or even disappears in other directions.

If a photosensitive film is placed behind the crystal, the X-ray diffraction pattern will be obtained.

Crystal X-ray diffraction is a highly dependent characterization method at present.

It can be said that in the eyes of professionals engaged in synthesis, getting the crystal is the same as the old driver knowing the serial number. You can find the small film at any time... Cough, you can determine the crystal structure at any time.

But according to Wang Qiang, crystal X-ray diffraction can not analyze the structure of monster crystal.

Then this is a big problem

Students who have studied chemistry seriously should know.

Solids are divided into two concepts: crystalline and amorphous.

The scientific method to distinguish crystal and amorphous is X-ray diffraction.

But the monster crystal in front of Lin Li and others is very special:

It has a lattice structure - because the array cell is detected, and the lattice structure is obtained by the infinite translation of the array cell.

In other words, the monster crystal is a crystal, there is no doubt about it.

But at the same time, it can't analyze the structure by X-ray diffraction, that is, it can't find the covalent bond in it!

This is like the sudden emergence of a mobile phone at the existing level of science and technology. It has all the standard functions of mobile phones, such as taking pictures on the Internet and making calls.

But when you are ready to split it, you find that it has no battery, chip and a series of internal electronic components.

Yes, of course.

Although this situation is only one case at present, which belongs to a typical unknown case, it will not reach the point of a dark cloud.

Therefore, Lin Li quickly adjusted his mind.

He took a deep breath, seemed to have made up his mind and said to Wang Qiang:

"Get on the Sims instrument and bombard it with Ar + ions!"

As soon as he said this, the whole laboratory suddenly fell into silence.

Sims instrument

Human words... Cough, scientific name is called secondary ion mass spectrometer

It can bombard the sample surface with high-energy primary ion beam, make the atoms or atomic clusters on the sample surface absorb energy, and sputter from the surface to produce secondary particles.

After these charged particles pass through the mass analyzer, the spectrum of sample surface information can be obtained.

At present, it is the equipment with the best penetration effect and the highest precision.

For example, our Zhurong rover in the previous paragraph is equipped with this set of instrument. There is a panoramic view of Zhurong rover on the Internet. The external port of SIMS instrument is about 30 ° in the lower right corner.

However, Sims technology has two defects:

First, its cost is very high, which is ridiculously high. Even if it is cool, it will have to work hard for several years.

Generally speaking, Ar + ions can blow off a micron of crystal surface in one night. If you change to monster crystal, the whole set of experimental cost may be large, eight or even nine digits.

After all, I'm afraid the ppb is not enough. At the beginning, you have to get the order of 10ppt to complete the task.

The second is

It may damage the monster crystal or even make it completely ineffective.

Because according to the current situation, the monster crystal lattice should be in a very complex form.

It does not even rule out the possibility of a trace of chaos - no matter how low the possibility is, it must be admitted in theory that it does exist.

Therefore, even if only 1 micron deep is blasted, it is likely to cause irreversible damage to the monster crystal at the micro level.

Therefore, this order is very risky.

Once the monster crystal has a problem at the micro level, it means that this isolated book will be completely scrapped.

However, Lin Li finally chose to take this step. Some risks must be borne when exploring the unknown.

Now, if you don't go on, you will be in vain as a scientific researcher.

However, he must be present in person, which is why he came to the scene - to put it mildly, if the monster crystal was really destroyed by the ion beam, as the camp leader and the famous Chinese biology authority, he would at most write a report.

It is impossible to be punished administratively.

But if he doesn't show up.

Even if it is ordered by long-distance communication, once there is an experimental accident, some of the responsibility will fall on Wang Qiang.

At that time, even if the little girl can stay in the camp, the relevant research authority will be shortened. At least she will have little chance to contact the anatomy of the third-order monster.

Therefore, as a teacher, Lin Li will never allow this to happen.

When everything was ready, Lin Li stood in front of the secondary ion mass spectrometer, while Wang Qiang assisted.

"Surface C of the target sample, the minimum area diameter is 80nm, and the bombardment deposition angle is 2teta!" (why can't I type the symbol?)

"The incident current is 10mac ㎡, and the ion concentration of the incident source is greater than 10 ^ 14atomsc ㎡!"

"High Energy Ar + ion beam is ready, energy 9659.6 EV!"

With the completion of several processes, a decisive white light flashed in the numerous lenses.

He waved and ordered:

"Instrument blast!"

Whew - Da——

A high-energy ion beam composed of Ar + bombarded the target surface of the monster crystal quickly, and the high-energy bombardment hit an extremely small amount of secondary ions.

Then these secondary ions are extracted into the field free drift tube and reach the ion detector along the established flight path.

Under normal conditions, the sputtering stripping rate of static SIMS is generally 0.1 nm per hour.

But now, regardless of the cost of the laboratory, Lin Li has adopted the dynamic SIMS mode, and the stripping speed of secondary ions on the surface of monster crystal has reached 100 microns per hour.

After all, we have to destroy the structure anyway. It's not as good as the way of higher power.

In the case that XRD can not be analyzed, let alone 0.1 nm, the damage of 0.1 flying meter or even 0.1 AMI is the same as waist cutting.

Just one hour later, the secondary ion mass spectrometer obtained the first batch of results.

The task of analysis is handed over to Wang Qiang and her elder martial Sister Li Yan.

Students who know about mass spectrometry should know it.

The abscissa of the secondary mass spectrum represents the mass charge ratio and the ordinate represents the intensity.

The signal intensity of the mass spectrum peak is actually an electrical signal, indicating a relative intensity.

Generally, within the detection quality range, the peak intensity with the highest signal intensity is 100%, and other peak heights are displayed in the proportion of 100%.

Under normal circumstances, a spectrum can only have one base peak. If there is more, it is generally due to abnormal equipment, problems with the ion beam, or problems with your eyes.

However, 50% of the peak heights of the secondary mass spectra in the hands of Wang Qiang and Li Yan are consistent - and the equipment and ion beam can never be non-conforming.

That's interesting.

"A few are fragment peaks, and the peak area is calculated by internal standard method..."

"The molecular weight difference between the mass number interval 236... And the cyclic section is 2..."

"This substance does not exist in the database... As expected..."

"Excluding the impact of matrix benefits..."

"Hmm? The degree of polymerization starts from 7? That is to say, there are covalent bonds inside it?"

"Yes, it's the peptide chain! The peptide bond in the peptide chain is broken... That is, can you distinguish B series ions or Y Series ions?!"

Suddenly, Wang Qiang's left hand was held high:

"Teacher, I analyzed it. It's Y2 ion!"

However, before Lin Li reacted, Wang Qiang's voice suddenly rose high and almost sharp:

"No, no! Teacher, there is a broken phase at the peak! There are three more hydrogen at the peak of Y ion.... it's impossible... Is this..."