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Chapter 239: Chapter 230: People Like You

Inside a lecture hall at Yan University’s School of Chemistry.

It was nine in the morning, and the hall was already about seventy or eighty percent full.

On the lecture stage, the elderly Zhang Lufang methodically organized her teaching notes, then pointed her laser pointer at the projection screen.

”Alright, class. Today, we’re going to continue our discussion from last time.”

”The d-d transitions of transition metal complexes, right?”

A yellowed Tanabe-Sugano diagram appeared on the screen. The x-axis represented the Ligand Field strength, Dq/B, and the y-axis represented the energy term, E/B. The space between was filled with a dense thicket of intersecting curves.

”We’ve previously discussed how the Ligand Field splits the five-fold degenerate d-orbitals of a free ion.”

”But what happens after the split?”

”Electrons don’t just jump between these new energy levels however they please, you see.”

The old professor picked up a piece of chalk and, stroke by stroke, wrote two words on the blackboard.

”Selection Rules.”

”The Laporte selection rule tells us...”

...

”The spin selection rule also tells us that spin multiplicity must be conserved before and after the transition.”

The old professor paused, her eyes narrowing as she scanned the students below.

”So, when we open our textbooks, we see that hydrated transition metal ions have very pale colors—the light blue of Cu²⁺, the pale green of Ni²⁺.”

”That’s because their d-d transitions are inherently forbidden under the Laporte selection rule, isn’t that right?”

”Then why can we still see color?”

”This involves vibronic coupling, d-p orbital mixing, and deviations from centrosymmetry in the molecular geometry...”

The old professor’s lecture pace was steady, each sentence following the last, neither rushed nor slow.

Below, the freshmen frantically took notes, while others aimed their phones at the screen, snapping a frenzy of photos.

And then there was Li Dong, sitting in the middle of the lecture hall.

He sat perfectly still, just listening.

A girl with glasses sitting next to him leaned over and gently nudged the boy beside her with her elbow.

”Hey, look at that guy in the middle.”

”How come he isn’t writing anything down?”

The boy looked up and was also taken aback.

”Professor Zhang’s lectures may be slow, but the content is really deep.”

”If you miss even one sentence, you’ll be completely lost when you look at the Tanabe-Sugano diagram later.”

”Is he just here to answer roll call for someone?”

Just then, another girl shook her head and lowered her voice.

”You don’t recognize him?”

The boy paused, confused.

”Who is he?”

The girl continued.

”That’s East God from Yuanpei College.”

The boy was even more dumbfounded. ’East God? West God? What’s all that? I don’t know him.’

Several seconds passed before it finally dawned on him.

”Hiss... Isn’t East God a math major?”

”What’s he doing here in our School of Chemistry?”

The commotion in their section.

Li Dong didn’t notice a thing.

He was busy recording the old professor’s lecture in his Memory Palace.

On the stage.

Zhang Lufang also noticed Li Dong, and the corners of her eyes crinkled into a smile.

”Now, let’s look at a problem.”

”A typical octahedral Co(III) complex, [Co(NH₃)₆]³⁺, has a strong-field, low-spin d⁶ configuration.”

”Using the Tanabe-Sugano diagram and the corresponding selection rules for electronic spectra... and explain why this complex shows only two observable absorption bands in its absorption spectrum.”

The old professor closed her book and pointed at Li Dong.

”The student in the middle.”

”You, answer the question.”

The classroom fell silent.

It wasn’t that they all recognized Li Dong.

It was mainly because of the question the old professor had posed...

Low-spin d⁶? Tanabe-Sugano diagram? Ground-state term symbol?

’Is that question even in human language?’

’Why can’t I understand any of it?’

At that moment, Li Dong also exited his Memory Palace.

He slowly stood up.

He could understand the question.

He had read some chemistry books before, like You Xiaoceng’s *Coordination Chemistry* and Teacher Xiang Sifen’s *Introduction to Emerging Fields of Inorganic Chemistry*.

Thanks to his Memory Palace, he still remembered them.

But he only understood the question; he didn’t know how to solve it.

So he could only shake his head with a wry smile.

”Teacher Zhang.”

”I... don’t really know how.”

On the stage, the old professor looked at the flustered Li Dong.

She waved her hand.

”If you don’t know, then sit down.”

The old professor leisurely pushed up her glasses.

”Remember to pay attention in class and not daydream, alright?”

”...”

Li Dong nodded hastily.

Then he cried foul internally.

’I wasn’t daydreaming...’

But he couldn’t explain it to anyone, so he could only pick up his pen and pretend to start taking notes along with the others.

When the other students saw that even the famous East God had been put in his place by the old professor,

their reverence for her deepened into fear.

...

The old professor continued to lecture for about another twenty minutes.

She went from the first absorption band of the electronic spectrum to the second, briefly touching upon the Jahn-Teller effect along the way.

Then she glanced at the clock on the wall.

”Alright, that’s all for today.”

”For homework, I want you all to redraw this Tanabe-Sugano diagram by hand for the d² through d⁸ configurations.”

”Just looking at it is useless. You have to do it yourselves, you see?”

Li Dong: ...

Only then did the bell signaling the end of class ring.

On the stage, a smiling Zhang Lufang waved Li Dong over.

Li Dong obediently went over to the old professor’s side and greeted her.

”Teacher Zhang.”

The old professor smiled and replied.

”What made you decide to come to my class today?”

”I heard from a few other professors that you’ve been in closed-door cultivation.”

”Have you reached the Grain Avoidance Realm?”

”Is that right?”

Li Dong gave a dry laugh and explained.

”No, no, it’s just... I get so absorbed in my studies that I sometimes forget to eat.”

Zhang Lufang waved her hand dismissively.

”Ah, that’s a wonderful spirit to have.”

”We were just like that when we were young. Once you start tackling a research topic, you can forget about day and night.”

”Not many of the young people today can endure that kind of hardship.”

After speaking, she looked Li Dong up and down again.

”However...”

”You came to my class today... I’m afraid you have something to ask me, don’t you?”

Li Dong was taken aback.

After Qi Yu’s words, a flash of inspiration had struck him, but he hadn’t been able to grasp it. So he did have a question, but he didn’t know what the question was.

’But how did she see through me?’

The old professor seemed to have seen his confusion.

”You remind me of an old classmate of mine from our university days.”

”Things we couldn’t figure out, he’d understand with just a single glance.”

”And there’s one thing you two have in common.”

”Right now, if you mention Yan University undergraduates, the first name that comes to mind in the entire Huaxia mathematics community is you, Li Dong.”

”He was even more impressive than you.”

”For anyone in the field of chemistry, if you mentioned Fudan University, he was the first person who came to mind.”

As the old professor spoke, she squinted, her eyes holding a nostalgic light.

”So, for people like you...”

”You can learn general textbook knowledge on your own. You don’t need to come all this way just to sit in on my class.”

”You came to my class today because you definitely have a question for me, right?”

Being praised like this by the old professor, Li Dong actually smiled a little sheepishly.

”You’re right... I do have a few questions I’d like to ask you.”

The old professor nodded.

”Let’s go, then.”

”We can talk in my office.”

When they got to the office, Zhang Lufang sat down in her chair, poured a cup of hot water from her thermos, and pushed it in front of Li Dong.

”So, tell me, what exactly is your question?”

Li Dong sat down in the chair opposite her.

But he didn’t speak for a long time.

After a good while,

”Teacher Zhang.”

”Actually... I don’t even really know what my question is.”

Zhang Lufang said, ”Oh,” showing no surprise.

”Then there must be a reason you suddenly had the thought to ask me something, right?”

Li Dong thought for a moment and briefly mentioned the meal from a couple of days ago.

He particularly emphasized Qi Yu’s summer camp research proposal—

identifying elements at the single-atom level, using an STM combined with synchrotron X-rays, and treating an element’s characteristic absorption edge as the atom’s ’fingerprint’ signal.

At this point, Li Dong paused.

”Normally, I would’ve just heard it and that would be that. I’m not familiar with this field.”

”But I keep feeling... like something flashed through my mind.”

”Just for an instant.”

”When I try to reach out and grab it, I can’t.”

”Don’t you think that’s a strange feeling?”

As he spoke, even he started to feel like he was talking nonsense.

The feeling was too vague; it was neither a concrete question nor a specific idea.

If he had to describe it, it was like a faint, barely-there thread connecting Qi Yu’s napkin diagram and that generational debate between Madam Curie and Mendeleev.

After listening, Zhang Lufang’s expression was a little peculiar.

She couldn’t quite understand it either, but she was reminded of her old classmate with the surname Fu.

’People like them don’t bother with small things.’

So she ventured a suggestion.

”Is it about orbital orientation?”

A BUZZ went through Li Dong’s entire being, and he froze on the spot.

The moment the old professor’s words fell, that once faint, barely-there thread suddenly materialized.

An STM can see the position of an atom, but it can’t tell what element it is.

X-ray absorption edges can identify elements, but you need at least ten thousand atoms to start. But if...

If, when an X-ray excites a core electron of an atom, it transitions to an unoccupied orbital...

And if that orbital happens to extend out in the direction of the STM tip, then the excited electron can tunnel directly to the tip.

The orientation of the orbital determines the efficiency of the tunneling.

This meant...

The tip could not only ”see” an atom, it could also ”recognize” what element that atom was.

It could even ”see” in which direction a specific empty orbital on that atom was pointing.

That wasn’t just the element’s fingerprint anymore.

It was a complete portrait of the single atom’s electronic structure.

The element’s identity, its chemical valence state, the orbital’s orientation... all obtained in one go.

Li Dong finally knew how to produce the data to stop the argument between Madam Curie and Mendeleev!

”That’s it!”

”Teacher Zhang, you’re amazing!”

”You pointed it out to me in a single sentence!”

Li Dong was overcome with excitement.

But Zhang Lufang just smiled.

”It’s not that I’m amazing.”

”It’s just that... a few academicians are also working on this.”