Prism Optics

Observations of Chemical Reactions at the Atomic Scale: Dynamics of Metal‐Mediated Fullerene Coalescence and Nanotube Rupture

“…[9] Under these conditions, the electron beam acts as an energy bath, promoting chemical transformations but not destroying the specimen, so that molecular dynamics and interactions can be observed in direct space at the atomic scale. It is not possible to measure the temperature of our nanotubes directly in TEM; however, provided that the nanotube has a good contact with the rest of the specimen (Supporting Information, Figure S2) the upper limit of heating by the electron beam is estimated to be 11 K above the temperature of the surroundings, [10] which is in good agreement with previous observations for nanotubes. [11] Ionization is less important for graphitic carbon owing to its high conductivity.…”

Design of a hybrid double-sideband/single-sideband (schlieren) objective aperture suitable for electron microscopy

“…Interestingly, it was once thought that placing an insulating probe (experiments described in 11 ) or fiber 22 at, or close to, the unscattered beam would be an effective way to introduce phase contrast. However, as one knows from experience with bare plastic sections, or when an unwanted piece of lint gets into the microscope column, the charging effects that occur with isolated insulators are quite severe and uncontrollable.…”

“…A related possibility is to block one half of the scattered wave completely, thereby producing what is called “schlieren” contrast in light microscopy and other optical applications 9 . In electron microscopy, masking off a half plane of the diffraction pattern has been referred to as the “Foucault method” 10 , and it has been said to produce “Foucault contrast” 10, 11 and optical shadowing 12 , but it is more commonly said (in the context of electron microscopy) to produce single-sideband (ssb) contrast 6 .…”

Beobachtung chemischer Reaktionen auf atomarer Ebene: Dynamik von Fullerenverschmelzung und Nanoröhrenbruch durch Vermittlung von Metallionen

“…Unter diesen Bedingungen treibt der Elektronenstrahl chemische Reaktionen an, jedoch wird die intakte Kohlenstoffnanoröhre (CNT, carbon nanotube) als Ganzes nicht zerstört, sodass die Dynamik und Wechselwirkungen von Molekülen auf atomarer Ebene direkt beobachtet werden können. Obgleich es nicht möglich ist, die Temperatur unserer Nanoröhre bei der Beobachtung im TEM zu messen, liegt die obere Grenze der durch den Elektronenstrahl verursachten Probenerwärmung 11 K über Umgebungstemperatur, [10] vorausgesetzt, dass die CNT einen guten Kontakt zum Rest der Probe hat (Abbildung 2S in den Hintergrundinformationen), was gut mit bisherigen Beobachtungen für Nanoröhren übereinstimmt. [11] Ionisation ist für graphitischen Kohlenstoff wegen dessen hoher elektrischer Leitfähigkeit weniger bedeutend.…”