摘要:

Conductivity measurements were made during the formation of alkali antimonides to deduce whether these materials arep‐type orn‐type conductors. Reproducible results were obtained, indicating that K3Sb and Na3Sb arentype while Cs3Sb and the multialkali antimonides areptype. A correlation between high‐quantum efficiency of photoemission andp‐type conduction is suggested.

ISSN:0021-8979    

DOI:10.1063/1.1722994

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Each of the noble gases, He, Ne, A, and Kr, has been ionically pumped with an energy of about 100 ev into a nickel target and has been subsequently released by a similar bombardment using a different noble gas. A mass spectrometer permitted the measurement of both the reemission of the trapped atoms and the trapping of the bombarding particles. The reemission mechanism is described in terms of a simple model which assumes that the trapped atoms are released by the bombarding particles through a mechanism of sputtering of either the target material or the trapped gas or a combination of both. The experimental results are in agreement with the model. A direct replacement of a trapped atom from its trapping site by a bombarding particle is shown to be a relatively unimportant factor in the reemission process. Measurements of the reemission rates of the trapped atoms have yielded information concerning the depth distribution of the trapped atoms in the nickel target. In particular, saturation of the depth distribution has been observed for Ne, A, and Kr at concentrations below one equivalent monolayer while He showed no such effects at the highest concentrations used, which corresponded to approximately 15 equivalent monolayers.

ISSN:0021-8979    

DOI:10.1063/1.1722995

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Penning has shown that at 500°C, Cu penetrates into Ni‐doped Ge (containing ∼1016Ni atoms cm−3) to a concentration more than 10 times its thermal equilibrium value. We have confirmed this observation and extended the experiments with the following results. At 500°C the rate of Cu64penetration (in Ni saturated samples) indicates an effective diffusion coefficientDeffof ∼2×10−8cm2/sec and a saturation density,n0, of ∼1016/cm3. No detectable Cu penetration occurs after 10 hrs at 400°C. The Cu penetration at 500°C is independent of dislocation density in the sample and also independent of whether or not the Ni has been previously precipitated. The extra Cu is not electrically active. We have similarly studied the rate of mixing of ordinary Cu and Cu64by diffusion in Ge samples at 500°C and find thatDefffor this process is again ∼10−8cm2/sec. From these experiments we conclude that Cu penetration in Ge is not responsible for the 0.04‐ev energy level which appears during the early stages of Ni precipitation at 400°C, as Penning suggests. The enhanced penetration of Cu64observed at 500°C may be interpreted as resulting from exchange between interstitially diffusing Cu64and precipitates of either Ni or Cu.

ISSN:0021-8979    

DOI:10.1063/1.1722996

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The changes in the electrical resistivity of metals at 78°K with elongation are investigated. Part I is devoted to the changes introduced in the face‐centered cubic metal aluminum upon elongation at 78°K. Part II discusses the changes that occur in the body‐centered cubic metal molybdenum upon elongation at 298°K. Both sections describe the relationship between the portion of the resistivity generally attributed to point defects and the resistivity that remains after the point defect recovery has been completed; these resistivities are proportional to each other for both metals.It is noted that for both metals the resistivity caused by point defects and the residual resistivity are directly proportional to the elongation. It is further discovered that the rate of resistivity recovery at 145°C for cold‐worked molybdenum is directly proportional to the amount of elongation introduced.

ISSN:0021-8979    

DOI:10.1063/1.1722997

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A general expression for the generation‐recombination noise in a two‐level impurity semiconductor is derived. Application is then made to zinc‐doped germanium in the dark from 20°K to 100°K. The total white noise in this case exhibits a maximum and a minimum as the temperature is increased and the contributions to the noise which can be associated with the individual levels vary.

ISSN:0021-8979    

DOI:10.1063/1.1722998

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The heat of formation of BaC2was determined by measuring the Ba pressure above BaC2+C using the Knudsen effusion method. The heat of formation of BaC2from the elements is &Dgr;Hf°298= −12.1±4 kcal/M.

ISSN:0021-8979    

DOI:10.1063/1.1722999

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The amount of wear of neutron‐irradiated diamonds relative to unirradiated ones is compared after a standard grinding against silicon carbide. It is found that the amount of wear increases with increasing irradiation, i.e., the diamonds become softer with increasing irradiation. Measurements of density show that it decreases with increasing irradiation. The decrease of cohesive energy of an irradiated diamond is estimated from the number of broken bonds and the strain energy of the density change. The experiments indicate that dislocation motion is not responsible for the wearing of diamonds.

ISSN:0021-8979    

DOI:10.1063/1.1723000

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The dynamics of electron beams from magnetically shielded guns is examined in detail both experimentally and theoretically. The electron orbits and beam shape variations are investigated with an electron beam analyzer which measures current density variations and transverse velocity. The existence of rings of charge that move through the beam and the gradual reduction in beam scalloping with length are demonstrated. It is shown that simple energy considerations plus an account of the role of transverse thermal velocities is sufficient to account for the experimentally observed features of beam behavior in the limit of negligible space charge. In the presence of space charge the beam behavior is qualitatively unchanged except for some defocusing and precession of the electron orbits provided that the magnetic field is at least several times the Brillouin field.

ISSN:0021-8979    

DOI:10.1063/1.1723001

出版商:AIP    

年代:1958

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1723003

出版商:AIP    

年代:1958

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1723004

出版商:AIP    

年代:1958

数据来源: AIP