Physicists at the University of Arizona have created the fastest microscope capable of observing electrons in motion. The device is an enhanced version of a transmission electron microscope designed to capture the movements of electrons using extremely short electron pulses.
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The Fastest Microscope operates with electron pulses as brief as one quintillionth of a second allowing it to capture images of electrons in real-time.
Given that electrons can travel at speeds of approximately 2,200 kilometers per second, this advancement is an achievement in physics.
Electrons are fundamental particles whose arrangements and movements within atoms and molecules are crucial to the study of physics and chemistry.
However their speed and tiny size have historically made them difficult to study in detail. With this new microscope scientists can now observe and analyze the quantum physics that govern electron behavior.
The ability to generate attosecond pulses, which are essential for observing electron movements was pioneered in the early 2000s. This breakthrough earned Pierre Agostini, Ferenc Krausz and Anne L’Huillier the 2023 Nobel Prize in Physics.
The University of Arizona team built upon these earlier advancements, generating a single attosecond electron pulse.
This development enhances the temporal resolution of electron microscopy, enabling scientists to freeze and observe electron motion with unparalleled clarity.
Traditional microscopes rely on camera shutter speeds for image quality, but this advanced microscope uses the duration of electron pulses to determine resolution. The faster the electron pulse, the sharper the image.
The Fastest Microscope uses a powerful laser split into two components to create the necessary pulses. The first pulse known as the pump pulse, energizes the sample prompting electrons to move.
The second, the optical gating pulse generates a brief time window during which a single attosecond electron pulse is produced.
The researchers have named this new imaging technique attomicroscopy. This method allows for the observation of electron dynamics at an atomic level, bridging the gap between material structure morphology and electron behavior.
Attomicroscopy provides a temporal resolution never before achieved, akin to using a high-speed camera to capture split-second moments.
The ability to see electron motion in real-time could revolutionize fields like material science and optoelectronics. The research team is already applying insights from this work to develop ultrafast optical transistors and lightwave electronics.
In chemistry attomicroscopy could allow scientists to control chemical reactions by observing and manipulating electron movements during bond formation and breaking leading to new methods in drug discovery.
The technology could also enhance cryo-electron microscopy allowing for the observation of electron behavior in biological molecules. This could lead to breakthroughs in understanding DNA structure and other biological processes.
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In comparison, a millisecond is a thousandth of a second, making it appear almost eternal against the backdrop of attoseconds. To illustrate, the ratio of attoseconds in one second is comparable to the number of seconds in 31.7 billion years, a time span more than double the age of the universe.
The shortest controlled event captured by scientists was 43 attoseconds. This achievement was previously celebrated as the briefest event ever created by humans.
The Nobel Prize-winning work of Pierre Agostini, Ferenc Krausz and Anne L’Huillier in 2023 laid the foundation for the current breakthrough.
Their pioneering work involved generating the first light pulses short enough to be measured in attoseconds.
Building on the Nobel laureates’ research, the University of Arizona team created the attomicroscope, an advanced electron microscope capable of capturing images at a speed of one attosecond.
This tool uses a series of processes to achieve this temporal resolution, allowing scientists to freeze time and observe electron motion that has been invisible until now.
The operation of the attomicroscope begins with a pulse of ultraviolet (UV) light directed at a photocathode, which releases ultra-fast electrons within the microscope.
A laser pulse is then divided into two beams. One of these beams is polarized and both beams arrive at slightly different times. This creates a gated electron pulse capable of imaging a sample such as graphene, at an attosecond temporal resolution.
This process enables the generation of electron pulses that last just one attosecond, allowing for the observation of ultrafast electron motion.
The ability to observe electron motion with such precision opens new doors in various scientific fields including quantum physics, chemistry and biology.
Understanding how electrons behave and move at this scale could lead to advancements in bioengineering, materials sciences and other disciplines that rely on understanding atomic and subatomic processes.
Traditional electron microscopes have been used to magnify objects to millions of times their actual size revealing details that are invisible to the naked eye.
The University of Arizona researchers addressed this limitation by generating a single attosecond electron pulse, as fast as the electrons themselves, which enhanced the microscope’s temporal resolution.
This breakthrough is analogous to using a high-speed camera to capture movements that would otherwise be imperceptible to the human eye.
The researchers’ work relied on splitting a powerful laser into two parts, a very fast electron pulse and two ultra-short light pulses.
The first light pulse known as the pump pulse provides energy to the sample causing electrons to move or undergo rapid changes.
The second light pulse called the optical gating pulse acts as a gate, creating a window of time during which the single attosecond electron pulse is generated.
By carefully synchronizing these pulses researchers can control when the electron pulses probe the sample allowing them to observe ultrafast processes at the atomic level.
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