Angana Mondal brings a new research group to ARCNL
As of January 1, Dr. Angana Mondal joins ARCNL as a tenure-track group leader. Her new research group, ‘Short-Wavelength Light Sources for EUV Metrology’, will explore the generation of light using liquids and novel materials, and how this can be applied to nanoscale imaging and metrology.
Intersection of expertise
Dr. Angana Mondal describes her career so far as being steeped in two different fields: laser-plasma physics and materials chemistry.
For her PhD at Tata Institute of Fundamental Research in India, she studied the generation of high-energy X-rays and electrons from plasma using small-scale laser systems and liquid methanol droplets. The relevant physics is similar to ARCNL research on extreme ultraviolet (EUV) radiation, generated using liquid tin.
Next, Angana moved to ETH Zürich to conduct postdoctoral research on high-harmonic generation in liquids. This also involves producing high-energy (EUV) radiation, but relies on the internal chemistry of the medium and light-matter interactions rather than turning the liquid into plasma.
Role at ARCNL and University of Amsterdam
Angana’s new role is a joint appointment at ARCNL and University of Amsterdam, as a tenure-track group leader and assistant professor. The position combines both areas of her expertise, and she’s proud of where her career has taken her. “I’m grateful to find a research niche that is so unique,” says Angana. “Four years ago, few people at the conference came to look at my poster. This year, I’ve been invited to give a talk at a big conference.” Angana brings this expertise to ARCNL, where she will focus on generating short-wavelength, high energy radiation for nanoscale metrology applications.
Generating high harmonics
In nanolithography and other computer chip manufacturing processes, the interaction between light and materials can cause defects on the nanometer scale. To be able to measure such small-scale defects with light, the wavelength of the light needs to be extremely short, which also means high energy.
One way to produce such light is with high-harmonic generation (HHG), a technique in which laser light shines into a material and interacts with the internal atomic/molecular structure, in such a way that light with shorter wavelength and higher energy is produced. The wavelengths produced are very specific, like how on a string instrument, only certain notes can be played as higher harmonics. In this way, the higher harmonics of light that are produced with this technique depend on the original laser wavelength, as well as the material that is used.
Novel materials and nanoscale metrology
In a gas, the atoms have higher ionization energy than those in a solid or liquid, so they can produce higher-energy light in HHG processes. However, the atoms are also more spaced apart, so there are fewer laser-atom interactions, and less light is produced.
On the other hand, solids are very efficient at producing a lot of light via HHG. But they are also more susceptible to heat damage if pushed to high energies, so they are more limited as short-wavelength HHG sources.
To find an optimal middle ground, Angana’s ‘Short-Wavelength Light Sources for EUV Metrology’ research group at ARCNL will focus on liquids and other novel materials. For example, two-dimensional materials are sheets of single molecules. “They can be layered on top of each other to form a custom material,” explains Angana, “making them more tunable than bulk solids.”
Angana and her group will explore all kinds of new media for short-wavelength light generation, from solids to gases to the liquids in between, in different combinations and configurations. At the same time, they will develop light sources with metrology in mind, driving fundamental research with industrial inspiration.
More information
If you have questions about the new research group or Angana’s appointment, please contact institute manager Marjan Fretz (Email: M.Fretz@arcnl.nl).
