Chapter 100: AES

The next morning, Ge Xinxin arrived at the laboratory. She took down the dried glass plates and brought them back to her office, comparing them one by one with the photos stored on the back for exposure.

“This one, hmm, it’s too dark. Ugh, it’s really troublesome to look at the negative colors. Never mind, let’s process it.”

She took out her Mac Pro, inverted the colors of the photos from the memory card in Photoshop, and then compared the details of the dark and light areas with the plates. After repeated comparisons, she found that the exposure of the plate taken at a shutter speed of 1/25 was closest to the exposure of the digital negative taken at 1/100, and the plate taken at 1/12 was closest to the digital negative taken at 1/50.

“Very good, ASA 12. This batch is set.” She recorded this number in her small notebook, then shut down and locked the computer.

Ge Xinxin was busy outside for several days, making several trips to the industrial sector’s main machinery factory. Although she had the approval of the Planning Department, the oxyhydrogen welder she had applied for was not immediately available. Since its successful trial production, only a few of these machines had been made, and the industrial sector itself was arguing over how to allocate them. It was obviously impossible to get one for the laboratory right away. The machinery factory’s reply was to get in line.

“So, what number am I in line?”

“Number 13, I guess,” Zhan Wuya, covered in oil and grime, said, picking up one of the many wooden clipboards scattered on his desk.

“That’s not a very lucky number,” Ge Xinxin said. “Can I move up one spot?”

“Then let’s make it 14,” Zhan Wuya said with a slight smile. “14 isn’t lucky either. How about a very lucky number, like 16? 18 would also work.”

“No, no, I’ll stick with 13,” Ge Xinxin said with a slightly regretful smile. “How many days will it take?”

Zhan Wuya looked at the “Overall Production Plan” on the wall and said, “Optimistically, about six months.”

“Six months!”

“About six months,” Zhan Wuya said. “This thing needs direct current. We can’t make qualified transformers right now, so we have to install a generator for each place that’s going to use an oxyhydrogen welder…”

“Alright, but you have to deliver it to my door.”

“Of course. I wouldn’t dare let you use it directly. Otherwise, if you burn down the laboratory, both seasons will come after me. Delivery and installation included…” Zhan Wuya casually wrote a queue number slip and handed it to Ge Xinxin. “I’ll have someone install it when it’s ready. Do you know how to use this thing?”

“I do—”

“I dare say you definitely don’t know how to use the one we make—it’s a ‘hardship version.’ Never judge the equipment of this world by the standards of the old world. Safety first,” Zhan Wuya said with a somewhat worried expression.

Ge Xinxin returned empty-handed. However, the experiment couldn’t wait. Since the oxyhydrogen welder couldn’t be resolved for the time being, the oxyhydrogen flame was out of the question. She had to settle for a Bunsen burner. After all, that’s what Bunsen himself used when he first observed spectra.

The project Ge Xinxin had spent so much effort on was to develop AES (Atomic Emission Spectroscopy) with the industrial level that the Yuanlao Yuan currently had and would soon be able to achieve.

Atomic Emission Spectroscopy is a method that uses the characteristic spectra emitted by the atoms or ions of each element under thermal or electrical excitation to determine the composition of a substance, for both qualitative and quantitative analysis of elements. It can be used to analyze about 70 metallic and non-metallic elements. This method can be effectively used to measure high, medium, and low content elements and is of great significance to metallurgy, the chemical industry, and materials science. It can be said that once this technology is mastered, it will be a qualitative leap for the Lin’gao industrial system.

The purpose of establishing the various central heavy industry laboratories was to provide quantitative and qualitative analysis services for raw materials, molten samples, and finished products in the metallurgical, cement, chemical, and other industries of the Lin’gao heavy industrial system. The methods were mainly chemical and physical analysis.

The analysis results that could be provided by such methods were relatively simple. Ge Xinxin’s intention was to use this project to conduct micro and semi-micro quantitative analysis in batches. Whether it was optical glass materials or metallurgy, they wouldn’t have to rely on whether macro analysis could detect a certain component, but could directly measure the components. This would be of crucial importance to some of the most critical industries in the Yuanlao Yuan’s industrial system that most needed a breakthrough: alloy materials, special steels, and optical glass.

Currently, the Ministry of Science and Technology had a batch of CCD spectrometers, including small devices like the Ocean Optics fiber optic spectrometer, some not much larger than a mobile phone, and equipped with special kits for rock, mineral, and metallurgical analysis.

Although the performance of these professional devices brought from D-Day was “god-like,” Ge Xinxin decided to completely rebuild this system using their own means. Otherwise, if the equipment was damaged, this link could be “lost” for a long time. This would be too great a loss for the Yuanlao Yuan’s industrial system, which needed to fill many gaps. Moreover, the number of devices brought was limited, and the scale of the Yuanlao Yuan’s industry was constantly expanding. It was impossible to equip every place with these rare and precious devices.

Two days later, two soldiers from the garrison battalion brought her a small wooden box marked “Confidential, Personal Delivery.” She opened the box. Inside was a Bunsen burner.

The Bunsen burner used coal gas, a fuel that was already very mature in the Lin’gao industrial system. The Central Heavy Industry Laboratory was specially equipped with a gas station that supplied gas to the entire laboratory building through pipes, making it very convenient to use.

The Bunsen burner was not difficult to manufacture, so the machinery factory had been self-producing this common heating tool for laboratories, capable of producing high temperatures, for a long time. The Lin’gao-made product was no different from a standard laboratory Bunsen burner, except for its appearance. It could reach a high temperature of 900°C in the outer flame.

However, a standard Bunsen burner could not be used directly. When Bunsen first tested spectra, he mainly used metal salt compounds, which he picked up with a platinum wire and then burned directly in the flame for observation. This method was relatively primitive. Ge Xinxin wanted to use the atomization method, which would give more accurate observation results.

The atomization method involves dissolving the sample in nitric acid or aqua regia, and then feeding the solution through a fine tube into the nozzle of an oxyhydrogen flame. The negative pressure created by the gas flow sucks it in and atomizes it. The atomized sample is then excited in the flame to emit light. Since she didn’t have an oxyhydrogen welder, she would first modify the Bunsen burner for temporary use. The Bunsen burner in the wooden box had been sent to the machinery factory for modification a few days ago. A fine tube had been connected to the nozzle to suck the sample solution into the nozzle.

Ge Xinxin carefully took out some equipment from the laboratory’s vault. These were all controlled materials collected from the Planning Department’s warehouse. She put on pure cotton knitted gloves and carefully mounted the equipment on a rack she had ordered from the machinery factory a few days ago.

Among them were a convex lens and two boxes of gratings: one box of diffraction gratings and one box of reflection gratings. These fragile items could not be self-produced in Lin’gao for a long time and had to be used with care.

However, with careful maintenance and use, they could last for decades without a problem.

The detection light path she designed was: Bunsen burner flame - convex lens - slit - grating - slit - dark box - plate.

Before that, she had made a series of preparations. First, she took recrystallized and purified sodium ferrocyanide and sodium chloride, broke up the complete, flawless crystals, and prepared a series of solutions with concentrations from 0.1M to 10^-8M.

The so-called sodium ferrocyanide, also known as yellow prussiate of soda, is a pale yellow crystalline substance. She planned to use this as a basic reagent. The reason she chose this compound was that it was a compound that the Yuanlao Yuan’s chemical industry could supply in batches. It was produced by heating the waste oxides from the gas plant with lime to produce a calcium ferrocyanide solution, then adding a boiled salt solution, and then heating it with a sodium carbonate solution, followed by concentration and crystallization.

After lighting the Bunsen burner, she inserted the fine tube installed on the burner into pure water. The pure water used in the laboratory was laboratory-grade secondary water prepared by multiple distillations in quartz vessels in the reagent room. It was usable.

Then Ge Xinxin opened the 1st, 4th, and 7th slits and exposed for 10 minutes to capture the spectrum of the blank solution.

Next, she replaced the solution with 0.1 mol/L sodium ferrocyanide, opened the 2nd, 5th, and 8th slits, and exposed for 5 minutes to capture the spectrum emitted by the excited sodium ferrocyanide solution. She then replaced it with pure water and rinsed the fine tube with pure water for 2 minutes.

Then she replaced the solution with 0.1 mol/L sodium chloride, opened the 3rd, 6th, and 9th slits, and exposed for 5 minutes to capture the sodium chloride spectrum. She then replaced it with pure water and rinsed the fine tube with pure water for 2 minutes.

She moved the plate up by 2 cm, captured the spectrum of 10^-2 mol/L sodium chloride, and similarly captured spectra down to 10^-8 mol/L, as well as NaCl of an unknown concentration (~10^-3 mol/L).

After the shooting was completed, Ge Xinxin packed up the experimental equipment—she didn’t dare to let the trainee experimenters handle things like the gratings. She removed the dark box, drew the curtains, lit the red paper flashlight, and took out the developing equipment, developer, and fixer she had prepared a few days ago to develop and fix the glass plates.

After obtaining the grating photos, she projected them on an enlarger and superimposed them with a pre-printed standard iron spectrum.

By comparing the Na spectrum with the standard iron spectrum, she located each wavelength of the standard iron spectrum and subtracted the corresponding background of pure water and sodium chloride. Then she looked up the relevant tables, compared the grayscale of the seventh to ninth order spectral lines of NaCl at various concentrations, and obtained the linear range of the glass plate. She also estimated the concentration of the unknown solution.

She used AgNO3 to titrate Cl- to determine the NaCl concentration and compared it with the semi-quantitative estimation by AES. She found that the difference was not large, so it could be used.

After the entire experiment was completed, Ge Xinxin was quite satisfied with the results. The next step, she planned to use a CCD spectrometer to compare and calibrate today’s experimental results. But, broadly speaking, spectrographic atomic emission spectroscopy could be considered successfully developed. This 17th-century black technology was halfway to success.