From: mk_thisisit
Ultrashort light pulses, specifically those in the attosecond (one billionth of a billionth of a second) and femtosecond (one millionth of a billionth of a second) ranges, are revolutionizing the ability to observe and understand ultrafast processes within atoms and molecules. This technology has significant implications, particularly in the fields of medicine and diagnostics, by allowing scientists to peer into the atomic interior and characterize the incredibly fast dynamics of complex biological systems [01:22:00], [01:25:00], [04:08:00].
Development and Significance of Attosecond Pulses
The creation of light impulses lasting less than one billionth of a billionth of a second was recognized with a Nobel Prize, enabling unprecedented insight into the atom’s internal structure [01:17:00], [01:22:00]. Professor Maciej Lewenstein made a significant contribution to this field [01:38:00].
While femtosecond pulses were previously honored with a Nobel Prize for enabling the study of slower molecular vibrations and rotations [03:08:00], attosecond pulses operate on a time scale 1,000 times shorter [04:58:00]. This allows for the observation of events that occur at the atomic level, such as the motion of nuclei in chemical reactions when a laser is shone into a molecule, leading to dynamics resembling “spaghetti that’s boiling” [03:33:00], [04:00:00].
The Lewenstein Model
In the 1990s, Professor Lewenstein, along with Nobel laureate Anne L’Huillier and Mikhail Ivanov, developed a fundamental article in attosecond physics [05:05:00], [09:35:00]. This paper provided a fully quantum description of the high-harmonic generation (HHG) process, which produces attosecond pulses [09:44:00], [09:48:00]. HHG involves shining a strong, short laser pulse onto a target (atoms, molecules, or solid bodies), exciting them to produce photons with frequencies that are multiples (harmonics) of the laser’s frequency [05:35:00], [06:03:00].
The process is described by a “three-stage model” or “simple man model” [08:10:00]. It begins with a single active electron tunneling through the Coulomb potential barrier of its atom due to the strong laser field, becoming almost free [07:13:00], [07:28:00]. The electron then accelerates in the laser field, changes direction as the laser oscillates, and returns to the parent ion or nucleus, where it recombines and produces harmonics [07:43:00], [07:57:00].
The Lewenstein model, also known as the strong field approximation, offers “quite simple formulas” that are frequently used by experimentalists to compare with their data, making it highly cited in the field [10:13:00], [10:31:00], [10:50:00]. This work has opened up many previously unknown possibilities, particularly in controlling the dynamics of complex systems [12:08:00], [12:14:00].
Medical Applications
Attosecond technology allows for the creation of a “camera” capable of operating at timescales of one billionth of a billionth of a second [12:45:00], [12:53:00]. Though the generated pulses are weak, they are strong enough to interact with atoms, moving not only outer electrons but also inner ones [13:42:00], [13:59:00]. This capability is crucial for understanding the “damn fast” dynamics within atoms [14:11:00].
The applications of these ultrashort pulses in medicine are an area of active research. While Professor Lewenstein himself hasn’t directly worked on medical applications, others, like Ferenc Krausz, are actively engaged in this field.
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Cancer Diagnostics: Research, particularly within Europe’s Extreme Light Infrastructure (ELI) laboratories in Hungary and Romania, focuses on using short pulses for cancer diagnostics [14:30:00], [14:43:00], [15:06:00]. The idea is to penetrate complex molecules and biological cells with high-frequency photons to characterize their response to disturbance [15:13:00], [15:31:00], [15:40:00]. The hope is that cancer cells might react differently to these pulses than non-cancerous cells, providing a diagnostic method [17:03:00], [17:06:00].
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Pump-Probe Experiments: Two types of attosecond pulses are produced: sequences of pulses and single isolated pulses [15:48:00]. Ferenc Krausz focused on single isolated pulses for “pump-probe” experiments [16:15:00], [16:20:00]. In this method, one pulse (the “pump”) is used to induce a change in a target, and then another pulse (the “probe”) is sent at varying time intervals to observe the target’s response [16:27:00], [16:45:00]. This allows for detailed characterization of the object’s dynamics [16:48:00], [16:50:00]. Applying this to biological cells could yield information about cellular behavior and disease states [16:56:00], [17:01:00].
These advancements in laser and photonic technologies are still developing, but they open up new avenues for understanding and interacting with matter at its most fundamental levels, potentially leading to breakthroughs in medical diagnostics and treatment.