⚛️ Zap! Picosecond Ion Pulses from Electron-Stimulated Desorption 🔬

The Main Idea

Scientists have developed a method to create ultra-short proton pulses using femtosecond photoelectrons, opening new possibilities for time-resolved studies of materials and surfaces.

The R&D

🔬 Imagine being able to watch atoms dance on a surface in real-time. That's exactly what a team of innovative researchers is working towards with their latest breakthrough in ion pulse generation!

Using a clever technique called ultrafast electron-stimulated desorption (UESD), scientists have managed to create proton pulses that last less than 500 picoseconds. That's quicker than a lightning strike! 🌩️

Here's how it works:

1. They start with a special cathode that emits electrons when hit by ultrashort laser pulses.
2. These zippy electrons then impact a stainless steel plate under ultra-high vacuum conditions.
3. The collision causes atoms (mostly hydrogen) adsorbed on the surface to desorb and ionize, creating our proton pulses.

What makes this method so cool? 😎 Unlike direct photoionization, which can suffer from a large starting volume due to laser focus limitations, UESD defines the starting plane of the ions with nanometer precision at a solid surface. It's like having a perfect launch pad for our atomic rockets! 🚀

The researchers demonstrated that they could produce pulses as short as 401 picoseconds after accounting for system jitter. They also showed that by adjusting the voltage applied to different parts of their setup, they could control the energy and timing of the ion pulses.

But wait, there's more! 🎉 This technique isn't just limited to protons. The team observed heavier ions like N+ and even molecular ions in their time-of-flight spectra. This versatility opens up a whole new world of possibilities for studying different materials and surface interactions.

Looking ahead, the researchers believe this method could be refined to produce ion beam pulses in the sub-picosecond range. Imagine being able to capture the birth of a chemical bond or the first moments of a phase transition! 🤯

This breakthrough paves the way for exciting new pump-probe experiments, where these ultrashort ion pulses could be used to initiate reactions or changes in materials, while another ultrafast probe (like a laser) captures the resulting dynamics.

As we continue to push the boundaries of what's possible in materials science and surface studies, techniques like UESD will play a crucial role in unraveling the mysteries of the atomic world. Stay tuned for more exciting developments in this fast-paced field! ⚡🔬

Concepts to Know

• Electron-stimulated desorption (ESD) 🔬: A process where electrons impact a surface, causing adsorbed particles to leave (desorb) from the surface. In this case, it's used to create ion pulses.
• Femtosecond 🕒: An extremely short unit of time, equal to one quadrillionth (10^-15) of a second. The laser pulses used in this research are this short!
• Time-of-flight (TOF) spectrum 📊: A measurement technique that determines the mass-to-charge ratio of ions by measuring the time it takes for them to reach a detector over a known distance.
• Picosecond ⚡: A unit of time equal to one trillionth (10^-12) of a second. The ion pulses generated in this research are in this time range.
• Pump-probe experiments 🔬💡: A type of experiment where one pulse (the pump) initiates a reaction or change, and another pulse (the probe) measures the results after a controlled delay.

Source: M. C. Chirita Mihaila, G. L. Szabo, A. Redl, M. Goldberger, A. Niggas, and R. A. Wilhelm. Generation of ultrashort ion pulses from ultrafast electron-stimulated desorption; https://doi.org/10.1103/PhysRevResearch.6.L032066

From: Institute of Applied Physics