A Scientific Legacy Rooted in Precision and Curiosity
In the heart of Riga, Latvia, a group of theoretical physicists began shaping the course of
atomic and molecular physics long before the age of digital supercomputers and high-powered lasers. Known internationally as the
“Riga Group”, this team laid the groundwork for many of today’s key theoretical methods in
electron-atom interactions,
strong-field physics, and
multiphoton processes.
Founded in
1958 by
Dr. Vasilijs Veldre at the Institute of Physics of the Latvian Academy of Sciences, the Riga Group quickly became one of the most respected teams in the Soviet Union and, later, in the global physics community. Their mission was clear: to understand the
fundamental interactions between atoms and electrons, using rigorous mathematics and innovative theoretical frameworks.
Groundbreaking Research and Firsts in the Field
During the 1960s and 1970s, the Riga Group produced a number of influential publications in
J. Phys. B: Atomic and Molecular Physics, introducing advanced models that explained how electrons interact with atoms under slow collision conditions. Their work led to a
Latvian State Prize in 1967 — a remarkable achievement for theoretical physics in a small European nation.
This prize was awarded for the series of papers titled
“Theory of Slow Electron Collisions with Atoms,” authored by V. Veldre, R. Damburg, R. Peterkop, M. Gailitis, and E. Karule. These studies not only helped define
threshold behavior and
scattering cross sections, but also inspired a new generation of physicists in Latvia and beyond.
Particularly influential were the contributions of
Dr. Raimonds Peterkop and
Dr. Modris Gailitis, who pioneered the
Wannier threshold law studies and developed
close-coupling methods that became standard tools in collision theory.
International Recognition and Scientific Collaboration
The Riga Group’s scientific excellence did not go unnoticed. By the late 1970s, they were invited to participate in major international conferences and were even trusted to organize them. Notably, they hosted:
- ICAP VI (6th International Conference on Atomic Physics) in Riga, 1978 — led by Dr. R. Damburg
- ECAMP IV (4th European Conference on Atomic and Molecular Physics) in 1992 — organized by Dr. E. Karule
These events placed Riga firmly on the map of global atomic physics and showcased Latvia’s ability to lead high-level scientific dialogue, even during politically complex periods.
The Spirit of Scientific Independence
Throughout the 1980s and 1990s, the Riga Group maintained its commitment to
theoretical rigor and
academic independence. Despite pressure from administrative bodies to focus on applied or engineering-based research, the group refused to become a calculation service. Instead, they pursued deeper questions about
quantum mechanics,
atomic structure, and
electromagnetic interactions, eventually aligning with like-minded scientists at the
University of Latvia’s Computational Center.
This intellectual resilience became a core part of their identity, especially after Latvia regained independence in 1991. By 1994, the group was officially incorporated into the newly formed
Institute of Atomic Physics and Spectroscopy at the
University of Latvia.
Transition Into the Modern Era
Following Latvia’s regained independence in 1991, the country’s scientific landscape went through major restructuring. Many institutions that had once operated under the Latvian Academy of Sciences were integrated into the
University of Latvia. In this transformation, the
Laboratory of Theoretical Physics was relocated to the university in 1994 and became part of the newly established
Institute of Atomic Physics and Spectroscopy.
At the helm of this transition was
Dr. habil. Phys. Erna Karule (Gailīte), who had already been an integral part of the Riga Group for decades. Elected Head of the Laboratory in 1993, she helped steer the group through this complex institutional shift while preserving its core values: mathematical precision, theoretical depth, and academic freedom.
With state funding for science becoming more limited, the group turned to
Latvian Science Council grants and
international cooperation to sustain its research. Despite these challenges, the Riga Group never compromised its standards and continued producing impactful work in the field of
strong-field atomic physics.
Key Areas of Research
The modern research focus of the Riga Group expanded to include:
- Multiphoton ionization: How atoms absorb multiple photons to reach ionization levels.
- Above-threshold ionization (ATI): Situations where atoms absorb more energy than the minimum required to ionize.
- Interactions with half-cycle pulses: Extremely short, unipolar laser pulses that cause unique atomic responses.
- Wave packet dynamics in Rydberg atoms: How electrons in highly excited states evolve and “revive” in quantum motion.
These studies required both
quantum mechanical and
semiclassical methods, reflecting the group’s strength in combining abstract theory with real-world experimental observables. Much of this work was done in collaboration with
Dr. E. Andersons’ atomic theorists group and the
Computational Center of the University of Latvia, which provided crucial numerical support.
A Track Record of Publication and Impact
The Riga Group’s members have published extensively in respected journals, including:
- Journal of Physics B: Atomic, Molecular and Optical Physics
- Physical Review A
- Applied Physics B: Lasers and Optics
- Latvian Journal of Physics and Technical Sciences
Their work has contributed to a deeper understanding of
ionization processes,
field-induced spectral shifts, and
atomic behavior in extreme electromagnetic environments. These insights are not only foundational in physics, but also relevant for technologies such as
high-intensity lasers,
quantum control, and
plasma diagnostics.
The Legacy Lives On
More than six decades after its founding, the Riga Group continues to inspire both Latvian and international scientists. Its history reflects the resilience of curiosity-driven research, even in the face of institutional, political, and financial change. While many labs around the world have shifted toward application-heavy work, the Riga Group has shown that
pure theory remains essential — especially when it leads to new understandings that ripple across both science and technology.
As Latvia strengthens its presence in the European scientific space, the contributions of the Riga Group stand as a
testament to long-term academic excellence. They have not only advanced atomic theory but also mentored generations of physicists who now continue that work in universities and research institutions around the world.
