Chapter 1311 - AES

Early the next morning, Ge Xinxin came to the laboratory. She took down the dried glass negatives and brought them back to her office, comparing exposure with the photos stored in the camera back one by one.

"This one—hmm, too dark. Ugh, looking at negatives is really such a hassle. Oh well, I'll process it."

She took out her Mac Pro and inverted the colors of the photos on the memory card in Photoshop, then compared shadow and highlight details with the negatives. After repeated comparison, she found that the 1/25 shutter negative exposure most closely matched the 1/100 shutter digital image, and the 1/12 shutter negative was closest to the 1/50 digital image.

"Very good, ISO 12—that's the baseline for this batch." She recorded this figure in a small notebook by her side and shut down and locked away the computer.

Ge Xinxin was busy for several days running errands. She made special trips to the Industrial Sector's directly subordinate General Machinery Factory multiple times. Despite having Planning Commission approval, the oxyhydrogen torch she had requested wasn't immediately available. Since trial production had succeeded, only a handful of units had been manufactured in total, and the industrial sector was endlessly arguing over allocation. Getting one for the laboratory immediately was clearly impossible. The machinery factory's response was to take a number and wait in line.

"What number am I?"

"Let's say 13." The oil-smeared Zhan Wuya picked up one of the messy stack of wooden clipboards on the desk and looked at it.

"That's unlucky. Can I get moved up one number?"

"Then 14." Zhan Wuya smiled slightly. "14 is also unlucky. How about 16 for extra good luck? Or 18?"

"No, no, I'll stick with 13." Ge Xinxin laughed ruefully. "About how long will it take?"

Zhan Wuya looked at the "Production Plan Overview" chart on the wall. "Optimistically, about six more months."

"Six months!"

"That's about right—six months." Zhan Wuya said. "This thing runs on DC. Right now we can't make qualified transformers, so we have to install a generator at every location that plans to use one..."

"Alright, but you have to deliver it to my door."

"Of course. I wouldn't dare let you just take it and use it—otherwise if you burn down the laboratory, Ji Situi will hunt me down to the ends of the earth. Delivery and installation included..." Zhan Wuya dashed off a numbered slip and handed it to Ge Xinxin. "When it's ready I'll send someone to install it. Do you know how to use this thing?"

"I know how to—"

"I dare say you definitely don't know how to use the one we made—it's the make-do version. Don't judge equipment from this timeline by old-timeline standards. Safety first." Zhan Wuya looked worried.

Ge Xinxin returned empty-handed. However, experiments wouldn't wait. Since the oxyhydrogen torch couldn't be solved for now, an oxyhydrogen flame was out of the question. She'd have to settle for a Bunsen burner first. After all, that's what Bunsen himself had used when he first observed spectra.

The project Ge Xinxin had worked so hard to get approved was an attempt to develop AES—Atomic Emission Spectroscopy—using the industrial capabilities the Council currently had or would soon achieve.

Atomic emission spectroscopy used the characteristic spectra that atoms or ions of each element emitted when thermally or electrically excited to determine matter composition, enabling qualitative and quantitative elemental analysis. It could analyze approximately 70 metallic and non-metallic elements. This method was effective for measuring high, medium, and low concentrations. It held extremely important significance for metallurgy, chemistry, and materials science. Once this technology was mastered, it would represent a qualitative leap for Lingao's industrial system.

The purpose of establishing the various Heavy Industry Central Laboratories was precisely to provide quantitative and qualitative analysis services for raw materials, melt samples, and finished products across Lingao's heavy industry system—metallurgy, cement, chemistry, and other industries. The main methods available were chemical and physical analysis.

The results such methods could provide were relatively simple. Ge Xinxin's intention was to use this project for batch micro and semi-micro quantitative analysis. Whether for optical glass materials or metallurgy, they wouldn't have to hope that bulk analysis could detect certain components—they could directly measure them. This was critically important for some of the most crucial industries in the Council's industrial system that most needed breakthroughs: alloy materials, specialty steels, and optical glass.

Currently, the Science and Technology Department had a batch of CCD spectrometers, including compact devices like Ocean Optics fiber-optic spectrometers—some no bigger than a cell phone—with specialized kits for rock-mineral-metallurgical analysis and other applications.

Though this professional equipment brought on D-Day performed like "divine artifacts," Ge Xinxin was determined to rebuild this system entirely through indigenous means. Otherwise, once the equipment was damaged, this capability could be "lost" for a long time. For a Council industrial system that needed to fill many gaps, such a loss would be too great. Moreover, the quantity of equipment brought was limited, and the Council's industrial scale was constantly expanding—impossible to equip everywhere with these scarce and precious devices.

A couple of days later, two Garrison Battalion soldiers delivered a small wooden crate marked "Classified, Addressee Only." She opened it. Inside was a Bunsen burner.

Bunsen burners used coal gas, a fuel already well-established in Lingao's industrial system. The Heavy Industry Central Laboratory was specially equipped with a gas station that piped gas to the entire laboratory building, making it very convenient to use.

Bunsen burners weren't difficult to manufacture, so the machinery factory had long since begun producing this high-temperature heating tool commonly used in laboratories. The Lingao-made product differed from ordinary laboratory Bunsen burners only in appearance. It could achieve outer flame temperatures of 900°C.

However, a ready-made Bunsen burner alone couldn't be used directly. When Bunsen originally tested spectra, he mainly used metal salt compounds, touching them to a platinum wire and directly observing them in the flame. This method was rather primitive. Ge Xinxin intended to use the atomization method—which produced more accurate observation results.

The atomization method involved taking sample solutions that had been digested with nitric acid or aqua regia, feeding them through a thin tube into an oxyhydrogen flame nozzle, and using the negative pressure from gas flow to aspirate and atomize them. The atomized sample was excited to emit light in the flame. Since she didn't have an oxyhydrogen torch now, she'd first modify a Bunsen burner as a substitute. The Bunsen burner in the wooden crate had been sent to the machinery factory district for modification a few days earlier: a thin tube had been connected to the burner nozzle for aspirating sample solution.

Ge Xinxin carefully removed some equipment from the laboratory's strongroom. These were all controlled materials obtained from the Planning Commission warehouse. She put on pure cotton knit gloves and carefully mounted this equipment on an equipment stand custom-ordered from the machinery factory a few days prior.

Among the items was a convex lens and two boxes of gratings: one box of diffraction gratings and one of reflection gratings. These fragile items couldn't be domestically produced for quite some time and had to be used with great care. However, with careful maintenance and handling, they could last for decades without problems.

The detection light path she designed was: Bunsen burner flame → convex lens → slit → grating → slit → plate holder → plate.

Before this, she had done a series of preparatory work. First she obtained recrystallized and purified sodium ferrocyanide and sodium chloride, broke intact flawless crystals, and prepared a concentration series from 0.1 M to 10⁻⁸ M.

The sodium ferrocyanide was also known as yellow prussiate of soda or yellow soda—a pale yellow crystalline substance. She planned to use this as a baseline reagent because it was currently one the Council's chemical industry could supply in bulk. It was produced by heating waste oxide from gas plants together with lime to produce calcium ferrocyanide solution, then adding boiling salt solution, heating with sodium carbonate solution, concentrating, and crystallizing.

After lighting the Bunsen burner, she inserted the thin tube into pure water. The pure water used in the laboratory was laboratory-grade secondary water prepared in the reagent room by multiple distillations using quartz vessels. It would do for now.

Then Ge Xinxin opened slits 1, 4, and 7, and exposed for 10 minutes to photograph the blank solution's spectrum.

Next she changed the solution to 0.1 mol/L sodium ferrocyanide, opened slits 2, 5, and 8, and exposed for 5 minutes to photograph the spectrum emitted by excited sodium ferrocyanide solution. She switched to pure water and rinsed the thin tube for 2 minutes.

She then changed to 0.1 mol/L sodium chloride, opened slits 3, 6, and 9, and exposed for 5 minutes to photograph the sodium chloride spectrum. She switched to pure water and rinsed the thin tube for 2 minutes.

She shifted the plate upward by 2 centimeters and photographed the spectrum of 10⁻² mol/L sodium chloride, and similarly photographed down to 10⁻⁸ mol/L, as well as an unknown concentration (~10⁻³ mol/L) of NaCl.

After completing the photography, Ge Xinxin put away the experimental equipment—she certainly didn't dare let an apprentice experimenter handle gratings and such. She removed the plate holder, drew the curtains, lit the red-paper flashlight, took out the developing equipment and developer/fixer she had prepared days earlier, and developed and fixed the glass plate.

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

By comparing the Na spectrum with the standard iron spectrum, she located each wavelength in the standard spectrum, subtracting the corresponding backgrounds of pure water and sodium chloride. Consulting the relevant tables, she compared the gray gradients of the Na seventh through ninth order spectral lines at each NaCl concentration to determine the linear range of this glass plate, and estimated the concentration of the unknown solution.

Using AgNO₃ to titrate Cl⁻, she determined the NaCl concentration and compared it with the semi-quantitative estimate from AES. Finding little difference, she confirmed it was usable.

After completing the full set of experiments, Ge Xinxin was reasonably satisfied with the results. The next step was to use the CCD spectrometer to compare and calibrate today's experimental results. But roughly speaking, photographic-method atomic emission spectroscopy could be considered successfully developed. This 17th-century black technology was half-accomplished.

(End of Chapter)