Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteiTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Scientists have captured the changing momentum-space pattern of electrons in an excited molecule using a femtosecond pump–probe experiment. The 2021 demonstration did not continuously film electrons or work on any molecule: it combined laser-based photoemission with a momentum microscope to track excited states in a specific dye-on-surface system.
What the experiment actually saw
In the study “Tracing orbital images on ultrafast time scales,” published in Science on 5 March 2021, Robert Wallauer and colleagues extended photoemission orbital tomography to excited molecular states. Earlier orbital tomography could map occupied orbitals; this experiment added time resolution and examined electrons temporarily promoted into unoccupied orbitals.
The instrument measured the angular and energy distribution of electrons emitted from the excited molecules, recording their full momentum-space distribution. That pattern provides evidence about the spatial distribution of the orbital from which the electrons came. It is an interpretation of measured photoelectrons, not a direct photograph of an electron moving through a molecule. The study connected the evolving excited-state signal with real-space excitation pathways.
How the pump–probe measurement works
- Prepare the sample. The reported demonstration used molecules of the organic dye 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) deposited on an oxidized copper surface.
- Excite the molecule. A first laser pulse, the pump, promotes an electron into a previously unoccupied molecular orbital.
- Choose a delay. After a controlled interval, a second pulse probes the excited state by photoemitting electrons into vacuum.
- Measure the emitted electrons. A momentum microscope records their energy and angular distribution, from which researchers infer the orbital’s momentum-space pattern.
- Repeat at different delays. Comparing measurements taken at different pump–probe delays reveals how the excited-state signal evolves and provides information about its lifetime.
“Real time” here means sampling the system at controlled delays with femtosecond-scale temporal resolution. The experiment is not a continuous video camera; each delay is a measurement point in a pump–probe sequence.
#1 Best Overall
- ★ ADVANCED LEARNING SCIENCE EDUCATION KIT --- Perfect chemistry model kit for modeling simple and small to more advanced and complex chemical structures for schools and college level, students of all ages, researchers and enthusiasts. Fun and interactive early learning molecular set for kids of all years and for use in the classroom.
- ★ HIGH QUALITY --- Made from high quality durable materials designed for easy construction and perfect fit. These Molecular Model Kit pieces are color coded to national standards for easy ID. Organic Chemistry Model Kit includes box for easy storage and transport with your other textbooks, notes, and books. Excellent for the classroom.
- ★ MOLECULE SCIENCE IN 3D --- We have prepared 252 Pcs molecular model set for you, This model contains C, H, O, N, P, S, F, CL, BR, I and other metals and a variety of single and double bonds, long bonds, long keys. Can be put high school, university chemistry in most of the organic or inorganic molecular structure model for the study of experimental operation.
- ★ QUICK AND EASY ASSEMBLY OF COMPLEX STRUCTURES --- Atoms and bonds that are perfectly suited to being connected and disconnected easily without making your fingers hurt. We’ve also included a link remover to make the task of diss.
- ★ CONVENIENT STORAGE --- The pieces come in a slim plastic box for convenient storage. See the pictures on this listing for a full understanding of what's inside!
Why the result matters—and what it does not show
Its significance is the combination of temporal information with orbital-sensitive momentum-space imaging. It lets researchers examine how an excited molecular state changes, rather than only mapping an occupied orbital in a static measurement. That is a step toward studying electron motion and excitation pathways with both time and spatial-orbital context.
- It was a specific demonstration. The reported sample was PTCDA on an oxidized copper surface, not a free-standing test of arbitrary molecules or reactions.
- The orbital image is inferred. Researchers interpret the photoelectrons’ angular and energy distribution to understand the spatial distribution of the source orbital.
- Broader chemistry applications remain prospective. The approach may support future work on photochemical reactions and electron-transfer processes, but this experiment did not establish a general-purpose method for filming those processes in any system.
What the apparatus required
In a 25 February 2021 report, Chemistry World attributed an estimate of €2–3 million for the equipment to study co-leader Ulrich Höfer. The estimate described the specialized femtosecond-laser and momentum-microscope combination at that time; it is a historical, attributed figure, not a current price or a verified market quote. The report said only a few suitable combinations existed worldwide then.
Rank #2
- ★ BASIC TO ADVANCED LEARNING --- Perfect for 16 Years and Over Teenages. Fantastic learning aid for your. If you have had one at home you can practice with your kids. Meanwhile if you are 16 Years and Over Teenages to playing with it by yourself to brush up on defunct chemistry skills. The pieces all to be sturdy and well made, and can use it for years to come.
- ★ FALL IN LOVE WITH CHEMISTRY --- These are so much fun to play with and they help you understand the relationship between molecules. Let you learn the shapes and chemical makeup of all the functions groups you'v so far learned in O-Chem and Inorganic chemistry.
- ★ HIGH QUALITY --- Made from high quality durable materials designed for easy construction and perfect fit. These Molecular Model Kit pieces are color coded to national standards for easy ID. Organic Chemistry Model Kit includes box for easy storage and transport with your other textbooks, notes, and books. Excellent for the classroom.
- ★ MOLECULE SCIENCE IN 3D --- We have prepared 178 Pcs molecular model set for you, This model contains C, H, O, N, P, S, CI, and other metals and a variety of single and double bonds, long bonds, long keys. Can be put high school, university chemistry in most of the organic or inorganic molecular structure model for the study of experimental operation.
- ★ CONVENIENT STORAGE --- The pieces come in a slim plastic box for convenient storage. See the pictures on this listing for a full understanding of what's inside!
Study and explanatory source
The primary study is R. Wallauer et al., “Tracing orbital images on ultrafast time scales,” Science 371(6533), 1056–1059 (5 March 2021), DOI: 10.1126/science.abf3286. Experimental setup and sample details above are also described in Kira Welter’s 25 February 2021 Chemistry World report.
Free tools Windows power users keep installed
One-click scans. No signup required.
Quick Recap
Best Value
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 240 Pcs Complete Set: The atom model kit includes with 86 atoms and 154 bonds, explore most the molecules structures from simple compounds to complex polymers.
- Effortless Assembly: Embedded component design ensures easy to construct Ball-and-stick and Space-filling models that maximizes focus on exploration without complex assembly.
- Durable & Portable: Built to last, the chemistry set is crafted from high-quality materials. Plus, its portable design allows you to take your experiments learning anywhere, between the home, classroom and lab.
- Essential Study Tool: Whether you're studying organic chemistry, biochemistry, or molecular biology, molecule building kit is an perfect learning tool for you deeper comprehension of molecular science.
Rank #4
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 444 Pcs Complete Set: The atom model kit includes with 136 atoms,158 bonds, and 150 fullerene model parts, explore most the molecules structures from simple compounds to complex polymers.
- Effortless Assembly: Embedded component design ensures easy to construct Ball-and-stick and Space-filling models that maximizes focus on exploration without complex assembly.
- Durable & Portable: Built to last, the chemistry set is crafted from high-quality materials. Plus, its portable Snap-Lock design allows you to take your experiments learning anywhere, between the home, classroom and lab.
- Essential Study Tool: Whether you're studying organic chemistry, biochemistry, or molecular biology, molecule building kit is an perfect learning tool for you deeper comprehension of molecular science.
Rank #3
- Great All-In-One Molecular Model kit for chemistry students at any age/stage
- Contains 281 pieces with 120 atoms and 160 Bond parts for both simple and complex structures
- Includes orbitals to model free lone pairs of electrons
- Includes multiple geometric configurations of carbons, metals and other atoms. Includes bonds to display ligands in coordination chemistry
- Highly durable plastic that are color coded to chemistry universal standards. Molecular tool included to quickly disassemble molecules and atoms connectors
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
