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1.
Respectively, 41 and 36 new cw far-infrared lasing lines have been observed using a waveguide resonator in CH3OD and CD3OD pumped by a low-pressure CO2 laser emitting in the 9.4, 10.4 m regular bands and in the 10.8 m hot band. The wavelength range was 46.6 m–1.67 mm in CH3OD and 53.6 m–1 mm in CD3OD. 相似文献
2.
Laser damage in silicon photodiodes 总被引:2,自引:0,他引:2
Thermal damage of silicon photodiodes exposed to intense optical radiation is investigated. Damage thresholds of Si photodiodes irradiated by 1.06m laser pulses are reported for values of irradiation time,, ranging from 10–8 to 1s. Threshold laser irradiation produces visible microscopic damage and a permanent degradation in photoresponse. The loss of responsivity is associated with degradation of the detector diode characteristics due to laser-induced heating. The time and wavelength dependence agree with the predictions of a thermal model which treats a semi-infinite material irradiated by a Gaussian laser beam. The energy density thresholds are independent of for short irradiation times and asymptotically approach a limiting behaviour which increases as for long times. They are given by the empirical relationE
0=65[1+217/tan–1(258)1/2] J cm–2 for 1.06m radiation. The thresholds at short irradiation times of detectors damaged by 1.06m radiation are about 25 times larger than those of detectors exposed to 0.6943m radiation. The greater susceptibility at 0.6943m is attributed to a larger optical absorption coefficient. 相似文献
3.
K. Nagamine 《Hyperfine Interactions》1993,82(1-4):551-561
The present paper summarizes new experimental proposals on muon catalyzed fusion (CF) research with a sharply pulsed negative muon beam now available at the UTMSL/KEK facility and soon to be available in a more extensive way at the RIKEN/RAL facility. Special emphasis is placed on (1) CF studies on ultra-pure D-T mixture, (2) slow – beam production via CF, and (3) some exotic CF phenomena. 相似文献
4.
I. I. Gurevich I. G. Ivanter B. A. Nikolsky A. N. Ponomarev V. S. Roganov V. I. Selivanov V. A. Suetin 《Hyperfine Interactions》1979,6(1-4):175-176
The paramagnetic state (+e–) in Si and Te was observed in a longitudinal magnetic field. The mean lifetimes of these states were obtained: Si = 1.45(3) s, Te = 12.5(8) s at 290 K, Te = 12(2) s at 250 K. 相似文献
5.
A novel atomic lens scheme is reported. A cylindrical lens potential was created by a large period ( 45 m) standing light wave perpendicular to a beam of metastable He atoms. The lens aperture (25 m) was centered in one antinode of the standing wave; the laser frequency was nearly resonant with the atomic transition 23
S
1–23
P
2 (=1.083 m) and the interaction time was significantly shorter than the spontaneous lifetime (100 ns) of the excited state. The thickness of the lens was given by the laser beam waist (40 m) in the direction of the atomic beam. Preliminary results are presented, where an atomic beam is focused down to a spot size of 4 m. Also, a microfabricated grating with a period of 8 m was imaged. We discuss the principle limitations of the spatial resolution of the lens given by spherical and chromatic aberrations as well as by diffraction. The fact that this lens is very thin offers new perspectives for deep focusing into the nm range. 相似文献
6.
Strong stimulated Raman emission has been observed on three Stokes' lines at 1.608, 1.744 and 1.896m from 12.6 km of single-mode silica fibre pumped at 1.50m with the output of a pulsed barium vapour laser. A study has been made of the spectral distribution of fibre output as a function of peak input power to the fibre (up to 47 MW cm–2), and the results are compared to theoretical predictions. Incomplete conversion of the pump to first Stokes', and first to second Stokes', lines is observed despite the length of the fibre. 相似文献
7.
C. Nieswand 《International Journal of Infrared and Millimeter Waves》1991,12(12):1487-1492
New cascade laser transitions of12CH2F2 at 172.50m, 208.83m, 220.44m, 223.99m and 250.61m are reported. A waveguide FIR laser was pumped with a quasi cw12C16O2 laser operating on the 9R32 line. Together with the already known lines at 184.3m, 196.1m and 235.9m, the laser lines can be assigned to rotational transitions in the 9 vibrational band of12CH2F2 and to refill transitions of the vibrational ground state 0. 相似文献
8.
Zero field SR spectra from Cr85Mo15 are well described by the sum of a lightly damped (0.02s–1<1<0.2s–1) and a heavily damped (2s–1<2<15s–1) exponential. The temperature dependence of these components is discussed in relation to the condensation of the incommensurate spin density wave and the onset of the antiferromagnetic state in this Cr-like alloy below TN=120K. Evidence is presented for the nucleation of the spin density wave at temperatures greater than 1.5TN. 相似文献
9.
G. Rideau 《Letters in Mathematical Physics》1979,3(3):229-235
It is shown that the generalized Lorentz gauges provide all linear conformal invariant gauges, i.e. gauges such that
A
=0. 相似文献
10.
Pierre van Baal 《Communications in Mathematical Physics》1983,92(1):1-18
We give a simplified construction of twist eating configurations, based on a theorem due to Frobenius. These configurations are defined through the equation:U
U
U
+
U
+
=exp(2in
/N) withU
SU(N), =1 tod andn
an antisymmetric matrix with integer entries. In the (Twisted)-Eguchi-Kawai model they yield extrema some of which survive forN. Comparison is made with the Monte Carlo data of the internal energy in the small coupling region. 相似文献
11.
I. L. Zhogin 《Russian Physics Journal》1991,34(2):105-110
Field equations for n-frames h
a
that are possible in the theory of absolute parallelism are considered. It is shown that in three cases the equations can, after the substitution h
a
=HpH
a
(H=det H
a
, p is an n-dependent constant), be written in a trilinear form that contains only the matrix H
a
and its derivatives and not H
a
. It is shown that the equations are still regular for degenerate but finite matrices H
a
if rank H
a
2.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 22–27, February, 1991. 相似文献
12.
μ+SR in magnetically ordered BCC metals: Local fields, μ+ sites,quantum diffusion,and strain effects
The paper gives a critical discussion of the procedures for extracting from the
+SR signals obtainable on magnetically ordered metals information on
+ sites, on local lattice distortions induced by the
+, on the local magnetic fields felt by the
+, and on quantum diffusion. Results for-Fe are:
+ occupy O sites, the tetragonality of the elastic double-force tensor isA–B 2eV, the dipolar magnetic field acting on the
+ isB
dip=(0.66±0.02)T. Using this information
+ hopping rates and diffusivities in Fe are deduced and compared with diffusivities obtained for hydrogen and deuterium. From this it is concluded that hydrogen in Fe diffuses via the adiabatic mechanism. In addition, the paper contains a brief summary of the theoretical background required for taking advantage of the rather large ¦A– B¦ values expected for
+ at O sites in bcc metals in order to gain information on the effects of energy asymmetries between neighbouring
+ sites on the + hopping rates. 相似文献
13.
It is shown that by taking advantage of the maximum in the spectral dependence of the coupling coefficient, very broad-band symmetric and asymmetric single-mode planar couplers can be designed. The symmetric coupler allows at least 95.6% coupling between the two cores over the wavelength range 1.3–1.58 m, while the asymmetric coupler can act as a 3 dB splitter with only ±1.6% variation in the splitting ratio over the wavelength range 1.3–1.67 m. In both cases, the design includes the curved input-output arms, and the estimated bend loss is approximately 0.1 dB. 相似文献
14.
P. Strasser K. Ishida S. Sakamoto M. Iwasaki E. Torikai K. Nagamine G. M. Marshall 《Hyperfine Interactions》1993,82(1-4):543-549
Slow – production via dd-CF using a two-layer arrangement is investigated. To determine its feasibility, experimental measurements are now in progress using the muonic X-ray detection method. The following experimental steps are being considered: (1) measurement of the number of – stopped inside a solid H2/D2 layer by detecting p K X-rays, (2) hot d emission detection by placing a secondary target at a distance of 10–30 mm from the layer and by detecting specific delayed X-rays, (3) measurement of the disappearance of d emission as the added D2 layer is increased, (4) dd-CF measurement by detecting fusion protons, and (5) slow – emission detection. Results of the initial test experiment are presented. 相似文献
15.
M. P. Rekalo 《Russian Physics Journal》1982,25(7):663-666
The angular dependence of the differential cross section of muon-pair formation in hadron-hadron collisions a1+a2+–+X is investigated in general form, attention being directed mainly toward those contributions to the differential cross section which are determined by the vector polarization of the incident hadron a1. The specific mechanism of processes a1 + a2 + + – +X is not given in detail here, but use is made of such general properties as the conservation of electromagnetic hadron current and the invariance of the electromagnetic interaction of hadrons with respect to spatial reflections.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 88–91, July, 1982. 相似文献
16.
U. Werling Wan Chong-Yi K. F. Renk 《International Journal of Infrared and Millimeter Waves》1985,6(6):449-457
The tuning characteristics of a uv preionized 20-atmospheres gas discharge CO2 laser with a novel and simple preionization scheme have been investigated. Continuous tunability in all branches of the 9.4 m and 10.4 m band with a total tuning range of more than 60 cm–1 without frequency pulling is demonstrated. Additionally, a study of the laser pulse behaviour was performed. 相似文献
17.
J. Imazato K. Nagamine T. Yamazaki B. D. Patterson E. Holzschuh R. Kiefl 《Hyperfine Interactions》1984,19(1-4):857-863
A
–SR signal in nickel was found representing the first observation of
–SR in ferromagnetic materials, and the hyperfine anomaly was determined to be –2.82±0.08% in comparison with the hyperfine field at dilute Co in Ni known from NMR. 相似文献
18.
G. C. Chukwumah 《International Journal of Theoretical Physics》1980,19(5):379-392
A few neutrino-induced tetramuon events have recently been reported by two experimental groups with a production rate of 10–6 for(
–
–
+
+)/ (
–). However, the rate for such events is not yet determined theoretically. In the present paper, we report on a detailed calculation of the rate in the framework of a heavy quark cascade mechanism, using the QCD-improved parton distribution functions parametrized by Buras and Gaemers, which have successfully fitted various experimental data. Our calculation for(
–
–
+
+)/ () accords well with the CDHS and FHPRW rate. The computed rate is also in accord with that obtained via the radiative charm model calculation, whereby the normal charm dimuon production is accompanied by a radiative
+
– pair. 相似文献
19.
L. A. Coldren R. S. Geels S. W. Corzine J. W. Scott 《Optical and Quantum Electronics》1992,24(2):S105-S119
Recent experimental and theoretical results from strained InGaAs/GaAs quantum-well vertical-cavity surface-emitting lasers indicate that relatively high-power, efficient devices are possible. On 10 m square devices cw output powers of more than 3mW at room temperature and 0.4 mW at 100°C are observed. Broad-area, 100 m diameter devices gave pulsed outputs of over 0.5 W and 60 m diameter devices provided more than 12 mW cw. The device parameters have been modelled and found to be consistent with theoretical predictions. The results generally indicate that considerable device improvements are still possible by reducing internal losses, series resistance and voltage and improving heat sinking. With current internal loss levels 30 cm–1, three InGaAs quantum-wells have been found to be optimum. 相似文献
20.
F. G. Van Den Berg W. Van Rijswijk W. R. Joosten W. J. Huiskamp 《Hyperfine Interactions》1985,22(1-4):579-584
Low temperature nuclear orientation experiments down to 2 mK on147GdFe,149GdFe,149GdGd and153GdGd have yielded the magnetic hyperfine interaction strength. Bhf as 31.0(1.6) NT, 28.3(2.0) NT, 33.8(4.7) NT and 13.3(2.1) NT respectively. From these values the respective ground state magnetic moments ¦¦ of147Gd,149Gd and159Gd were deduced as 1.12(20) N, 1.01(16) N and 0.40(8) N. 相似文献