Experiments on the diffraction of cathode rays

Abstract

[Plate 19.]1.M. L. de Broglie has introduced a theory of mechanics according to which a moving particle behaves as a group of waves whose velocity and wave-length are governed by the speed and mass of the particle. In fact if m0 is the mass for slow speed and v the speed of a freely moving particle, the wave-length is given by X = -v2!c2/m 0v, and the wave velocity V group velocity being v, the velocity of the particle. Here c is the velocity of light and it will be seen that the wave velocity is greater than c. There is nothing impossible in this because the waves are regarded as purely geometrical -" phase waves "-not as carrying energy. Compare, in ordinary optical theory, the case of substances, such as sodium, for which the refractive index , is less than unity. The above is for free space ; in the presence of a field of force V varies, and the consequent bending of the waves by refraction corresponds, on the new theory, to the deviation of the path of the particle by the field of force, on the old. The consequences of this theory have been worked out by de Broglie, Schrodinger and others and applied to problems in spectroscopy where they have provided the solution of several outstanding difficulties left by the older theory of orbits. In view, however, of the extremely fundamental nature of the theory it is highly desirable that it should rest on more direct evidence, and, in particular, that it should be shown capable of predicting as well as of merely explaining. Dymond* has obtained some remarkable results on the scattering of slow elec trons in helium which are of the general nature to be expected in this theory, but our knowledge of the structure of helium, together with the mathematical difficulties of the problem have so far prevented any exact comparision of the theory with experiment. Davisson and Kunsmanf and Davisson and GermerJ have obtained results on the reflection of slow electrons from the surfaces of crystals, especially nickel, which show good qualitative agreement with the

Development of an Ultrafast Low-Energy Electron Diffraction Setup

“…At the same time, G. P. Thomson independently made similar observations with faster electrons in a backscattering as well as in a transmission geometry [56,57].…”

Coulomb excitation of highly charged projectile ions in relativistic collisions with diatomic molecules

“…Studies on Young-type interference effects in atomic, electronic, and photonic collisions have a long tradition, dating back to the very first electron diffraction experiments [1,2] that confirmed the concept of wave-particle duality proposed by de Broglie [3] in 1923. From the beginning of the 1960s, investigations along this line usually dealt with the homonuclear diatomic molecules whose two centers are considered to be the natural analogs of Young's optical slits.…”

“…5 and 6, the values of the "critical" collision energy at which the cross section vanishes depend on the particular excited state. For example, while the 1s 1/2 2p 1/2 : J = 1 state cannot be populated for T p =465, 587, and 766 MeV/u, the "critical" energies for the 1s 2 1/2 J = 0 → 1s 1/2 2p 3/2 : J = 1 transition are T p = 502, 632, and 820 MeV/u. This state dependence arises from the sensitivity of the total cross sections (as well as alignment parameters) to the transition energy ω = E f − E i , an effect that is also predicted for the hydrogen-like ions [cf.…”

Interference effects in bound-free pair production in relativistic collisions of nuclei with molecules

“…Formulated almost a century ago [16] for matter particles, this concept was initially confirmed in electron diffraction experiments [17,18]. Since then, a large number of investigations have been performed in order to observe the wave nature of not only electrons but also of heavier particles such as, for example, atoms, dimers, and even fullerenes C 60 [19].…”