Publisher Correction: Angle-dependent interferences in electron emission accompanying stimulated Compton scattering from molecules

AbstractThe high brilliance of ultrashort X-ray pulses recently generated in free electron lasers will soon open the way to the investigation of non-linear processes that still remain inaccessible due to the smallness of the corresponding cross sections. One of them is stimulated Compton scattering from molecules. In this work, we investigate stimulated Compton scattering from fixed-in-space H2 molecules in the few-hundred eV photon energy range, where both dipole and non-dipole transitions are important. We show that the interference between dipole and non-dipole transitions leads to pronounced asymmetries in the electron angular distributions. These asymmetries strongly depend on molecular orientation, to the point that they can lead to electron emission in either the forward or the backward directions with respect to the propagation axis, or in both directions, or even in the orthogonal direction. This is in contrast with Compton scattering from free electrons or atomic targets.

Download Full-text

Historical Introduction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077670 ◽

1977 ◽

Vol 35 ◽

pp. 2-5

Author(s):

R. D. Heidenreich

Keyword(s):

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

50Th Anniversary ◽

Secondary Emission ◽

Wave Nature ◽

Nobel Prize In Physics ◽

Primary Electrons ◽

The U.S ◽

Mutual Agreement

This program has been organized by the EMSA to commensurate the 50th anniversary of the experimental verification of the wave nature of the electron. Davisson and Germer in the U.S. and Thomson and Reid in Britian accomplished this at about the same time. Their findings were published in Nature in 1927 by mutual agreement since their independent efforts had led to the same conclusion at about the same time. In 1937 Davisson and Thomson shared the Nobel Prize in physics for demonstrating the wave nature of the electron deduced in 1924 by Louis de Broglie.The Davisson experiments (1921-1927) were concerned with the angular distribution of secondary electron emission from nickel surfaces produced by 150 volt primary electrons. The motivation was the effect of secondary emission on the characteristics of vacuum tubes but significant deviations from the results expected for a corpuscular electron led to a diffraction interpretation suggested by Elasser in 1925.

Download Full-text

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109768 ◽

1978 ◽

Vol 36 (1) ◽

pp. 524-525

Author(s):

T. Koshikawa ◽

Y. Fujii ◽

E. Sugata ◽

F. Kanematsu

Keyword(s):

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Life Time ◽

Activation Process ◽

Beam Diameter ◽

Activation Temperature ◽

Electron Multiplier ◽

Activation Condition ◽

Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

Download Full-text

SEM analysis of DC magnetron sputtered beryllium films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106867 ◽

1988 ◽

Vol 46 ◽

pp. 960-961

Author(s):

E. F. Lindsey ◽

C. W. Price ◽

E. L. Pierce ◽

E. J. Hsieh

Keyword(s):

Fine Structure ◽

Electron Emission ◽

Secondary Electron ◽

Low Voltage ◽

Ion Beam ◽

Secondary Electron Emission ◽

Sem Analysis ◽

Fused Silica ◽

Grain Structure ◽

Silica Substrate

Columnar structures produced by DC magnetron sputtering can be altered by using RF biased sputtering or by exposing the film to nitrogen pulses during sputtering, and these techniques are being evaluated to refine the grain structure in sputtered beryllium films deposited on fused silica substrates. Beryllium is brittle, and fractures in sputtered beryllium films tend to be intergranular; therefore, a convenient technique to analyze grain structure in these films is to fracture the coated specimens and examine them in an SEM. However, fine structure in sputtered deposits is difficult to image in an SEM, and both the low density and the low secondary electron emission coefficient of beryllium seriously compound this problem. Secondary electron emission can be improved by coating beryllium with Au or Au-Pd, and coating also was required to overcome severe charging of the fused silica substrate even at low voltage. The coating structure can obliterate much of the fine structure in beryllium films, but reasonable results were obtained by using the high-resolution capability of an Hitachi S-800 SEM and either ion-beam coating with Au-Pd or carbon coating by thermal evaporation.

Download Full-text