Resolving rainbows with superimposed diffraction oscillations in NO + rare gas scattering: experiment and theory
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| Anzahl der Teile | 62 | |
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| Lizenz | CC-Namensnennung 3.0 Unported: Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
| Identifikatoren | 10.5446/38782 (DOI) | |
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26
00:00
LichtstreuungSensorNiederspannungsnetzElementarteilchenphysikGleitlagerVideotechnikDiffraktometerMaterialSternatmosphäreImpulsübertragungInterstellare MaterieComputeranimation
00:07
ImpulsübertragungVerbrennungskraftmaschineProzessleittechnikTeilchen
00:20
PotenzialhyperflächeImpulsübertragungComputeranimationDiagramm
00:28
RäderuhrImpulsübertragungProzessleittechnikMechanikModellbauerComputeranimationDiagramm
00:47
Pfadfinder <Flugzeug>ImpulsübertragungStark-EffektLichtstreuungSchlauchkupplungBildqualitätFernordnungImpulsübertragungAngeregter Zustand
01:15
ElektronenröhreLaserStark-EffektGauß-BündelPhase <Thermodynamik>Lichtstreuung
01:21
ElektronenröhreStark-EffektGauß-BündelMagic <Funkaufklärung>FahrgeschwindigkeitBeschleunigungSatz <Drucktechnik>Phase <Thermodynamik>RollsteigVakuumphysik
01:40
ElektronenröhreStark-EffektAtomistikBestrahlungsstärkeEdelgasatomAnstellwinkelProof <Graphische Technik>
01:44
ElektronenröhreStark-EffektAngeregter ZustandInfrarotlaserProof <Graphische Technik>ImpulsübertragungAtomistikFahrgeschwindigkeitElektronisches BauelementSensorEdelgasatomSpeckle-InterferometrieAnstellwinkel
02:05
KristallgitterBuntheitNiederspannungsnetzImpulsübertragungSpeckle-InterferometrieErsatzteilIntensitätsverteilungTiefdruckgebietBeschleunigungNanotechnologieFahrgeschwindigkeitReifStark-EffektRichtkopplerSchaft <Werkzeug>KalenderjahrSchnittmuster
02:50
ModellbauerKristallgitterSpeckle-InterferometrieNegativer WiderstandTeilchenrapiditätBreitbandübertragungKraft-Wärme-KopplungDiagramm
03:05
ImpulsübertragungTeilchenKristallgitterProzessleittechnikIntensitätsverteilungLichtstreuungDruckkraftDiagramm
03:39
SensorSpezifisches GewichtAtomistikAngeregter ZustandImpulsübertragungSatz <Drucktechnik>EdelgasatomDiagramm
Transkript: Englisch(automatisch erzeugt)
00:07
In interstellar media, the atmosphere and in combustion, molecular collisions play an important role. By studying collision processes between molecules, we can learn more about interactions between particles.
00:21
The interactions which actually take place are described by a so-called potential energy surface. Theoretically, we need quantum mechanics to fully describe what happens during a collision. However, these do not always give us a physical insight of the processes that take place. So sometimes we can use models based on classical mechanics to get a more intuitive picture of how a collision proceeds.
00:48
To fully understand molecular collisions, it is essential to study them with the greatest detail, both experimentally and theoretically. For a lot of systems, the experimental results are of lower quality than the theoretical predictions.
01:03
So in order to understand what really happens during collisions, we perform high -resolution collision experiments and compare our results with state-of-the-art theoretical predictions. This is how the experimental setup looks like to obtain a high-resolution scattering experiment. If you look in our lab, we start here with a beam of nitric oxide molecules in the gas phase.
01:26
They expand into vacuum and travel through a 2.6 meter long stark decelerator with which we can select these molecules with a specific velocity and a very high quantum state purity. The decelerator in reality looks like this.
01:43
When the molecules exit the stark decelerator, we let them collide with rare gas atoms under an angle of 180 degrees. After the collision, we state-selectively ionize the molecules using two lasers. With the velocity map imaging technique, we then map the velocity components of the molecules on our detector here.
02:05
If we measure a whole day and analyze our results, we obtain an image like this, which is a part of a circle. The colors represent intensity, the radius of the circle is the speed of our molecules, and the position on the circle is the angular distribution of the collision products.
02:23
Because of the unique and powerful combination of a stark decelerator and velocity map imaging, we get extremely high-resolution images, resulting in a very narrow ring. In this ring, we can resolve structures that could not be resolved before. In this image, you see an alternating pattern of high intensity and low intensity.
02:46
These kind of structures are even better visible if we look at the three-dimensional representation of another typical experimental image. We see broad structures with rapid oscillations on top. We can explain the origins of the different structures using semi-classical models and quantum mechanical theory.
03:05
The structures are caused by different pathways of the collision partners, resulting in the same amount of deflection. This is what you can see here, for example. If two particles approach each other, it depends on how they approach, whether they will feel attraction, repulsion, or both.
03:24
Different processes can now lead to the same deflection angle, resulting in a build-up of intensity. This strongly depends on the potential energy surface, describing the interactions between the collision partners. In general, we found excellent agreement between our experimental results and theoretical predictions.
03:45
Because of our high experimental resolution, we even resolved a specific feature for nitric oxide molecules, colliding with argon atoms, that is found to be extremely sensitive to the precise shape of the potential energy surface. In this way, we could distinguish between two high-quality, state-of-the-art potential energy surfaces.
04:06
The collisions between nitric oxide molecules and rare gas atoms are in principle well-known and often studied. But this study shows that with our high experimental resolution, we can still find surprises and challenge theory. In the future, our experimental approach could be used to study less-known
04:25
systems, for which experimental validation of the potential energy surfaces is still needed. For example, collisions between two molecules, which are theoretically much more difficult to understand.