The series spectra of the stripped boron atom (BIII)

In a preceding article [1], we have brought forward evidence that in "hot spark" spectra the strongest lines generally correspond to atoms from which the valence electrons have all been stripped off, so that the resulting spectrum is hydrogen-like, i.e., is due to one single electron moving between the series of levels characteristic of a simple nucleus-electron system. For such a nucleus-electron system the Bohr theory in its elementary form [2] which dealt only with circular orbits, i.e., with variations in azimuthal quantum numbers, the radial being always zero, yielded at once the result that the energies corresponding to a given quantum state, e.g., quantum number 1, increased in the ratio 1, 4, 9, 16, etc., as the nuclear charged increased in the ratio 1, 2, 3, 4, etc. This meant physically that the frequencies corresponding to jumps from infinity to an orbit of given quantum number, technically called term-values, when divided by the square of the nuclear charge should come out a constant; otherwise stated that the constant term in the Rydberg formula should become N, 4N, 9N, 16N

Ideal isotropic auxetic networks from random networks

Auxetic materials are characterized by a negative Poisson's ratio, $\mathrm{\nu}$. As the Poisson's ratio becomes negative and approaches the lower isotropic mechanical limit of $\mathrm{\nu = -1}$, materials show enhanced resistance to impact and shear, making them suitable for applications ranging from robotics to impact mitigation. Past experimental efforts aimed at reaching the $\mathrm{\nu = -1}$ limit have resulted in highly anisotropic materials, which show a negative Poisson's ratio only when subjected to deformations along specific directions. Isotropic designs have only attained moderately auxetic behavior, or have led to structures that cannot be manufactured in 3D. Here, we present a design strategy to create isotropic structures from disordered networks that leads to Poisson's ratios as low as $\mathrm{\nu = -0.98}$. The materials conceived through this approach are successfully fabricated in the laboratory and behave as predicted. The Poisson's ratio $\mathrm{\nu}$ is found to depend on network structure and bond strengths; this sheds light on the structural motifs that lead to auxetic behavior. The ideas introduced here can be generalized to 3D, a wide range of materials, and a spectrum of length scales, thereby providing a general platform that could impact technology.Comment: 16 pages, 6 figure

Series spectra of two-valence-electron atoms of boron (BII) and carbon (CIII)

Series spectra of BII and CIII.—By methods previously reported in the identification of lines in the extreme ultraviolet, 13 lines in addition to the pp′ group of BII have been identified, completing the classification of all lines known to be due to BII. Taking the 4f level as 27800 (probably correct to within 200 frequency units), the following term values were obtained for BII: 3s, 72930.8; 4s, 36655.5; 2p1, 165343.9; 2p2,3, 165362.7; 3p1, 59006.5; 3p2,3, 59010.0; 3d, 52054.2; 4d, 28640.4; 5f, 17795.7; 2S, 194325.9; 3S, 66665.1; 2P, 120929.4; 3D, 48410.3. In the case of CIII, 8 lines in addition to the pp′ group were identified, and taking the 4f level as 62600, the following term values were obtained for CIII: 3s, 146197.2; 2p, 331939.2; 3p1, 124685.8; 3p2, 124698.6; 3p3, 124704.1; 3d, 114387.2; 2S, 375463.1; 2P, 273111.0. Progression of frequency separations and of screening constants for regular doublets for Li to O is shown in Table VI, for one to six valence electrons. The separation (2p2-2p1) or (2p3-2p1) regularly decreases and the constant s regularly increases, for a given element, with the number of valence electrons, irrespective of the fact that both doublets and triplets are involved

High frequency rays of cosmic origin I. Sounding balloon observations at extreme altitudes

Discharge rate of an electroscope at altitudes from 5 to 15.5 km.—Four specially designed instruments, each comprising a recording electroscope, thermometer and barometer and each weighing but 190 gr were sent up with sounding balloons from Kelly Field, Texas. Three were recovered and of these two had satisfactory records of their flight during which they reached altitudes of 11.2 and 15.5 km, respectively. A comparison of the recorded electroscope reading at the 5 km level during ascent with the reading at the same level during descent shows that the average discharge rate of the electroscopes while above the 5 km level was about three times their discharge rates at the surface of the earth, and corresponded to an average rate of production of ions of 46.2 ions per cc per sec. This is only 25 percent of the value to be expected from the observations of Hess and of Kolhörster and constitutes definite proof that there exists no penetrating radiation of cosmic origin having an absorption coefficient as large as 0.57 per meter of water

The extension of the X-ray-doublet laws into the field of optics

Application of relativity formulas for x-ray doublets to ultra-violet spectra.— Evidence has been presented which indicates that many of the strongest lines in hot spark spectra are due to atoms stripped of all valence electrons excepting the one which in jumping between energy levels emits the radiation. For the L doublets due to atoms with but one L electron, Li(+), Be(2+), B(3+), C(4+), it is found that the frequency difference varies with atomic number Z in accordance with the relativity formula for x-ray doublets Δν=K(Z-s)4, the constant K being.365 for the regular L series, and the screening constant s decreasing from 2.02 for Li(+) to 1.86 for C(4+). Other L doublets are attributed to atoms stripped of all but three L electrons, the same formula holding but giving values of s about 20 per cent greater. In the case of triplets, the frequency differences of the widest pairs give values of s for atoms stripped of all but two or four L electrons which agree well with values for only one, three or five L electrons, though tending to be somewhat greater. Similarly from M doublets and triplets (K=.108) of C and N, values of s were obtained for atoms with from one to three L electrons slightly greater than from the corresponding L lines. In the case of atoms with only one M electron, the values of s decrease from 7.45 for Na(+) to 5.74 for P(5+), corresponding values of s from N, O and P series of doublets being slightly larger; for atoms with only two M electrons (widest pair of triplets) and with only three M electrons (doublets) the values of s vary up to about 9. For doublets corresponding to outer transitions 3d2-3d1, 4d2-4d1 and 4f2-4f1 the values of s come out close to 10. In the case of irregular L and M doublets corresponding to transitions from the 2s and 3s levels, the law for corresponding x-ray doublets also holds, the differences (sqrt[νs]-sqrt[νp]) increasing regularly and not very greatly with Z. All these facts are shown to agree well with what should be expected according to the Bohr-Sommerfeld theory; and the values of s give quantitatively the influence upon the effective nuclear charge of the addition of electrons in the valence shells. New series terms. The above relations enable the value of s for a given series for a given ionized atom to be predicted, and led to the discovery of an L doublet at λ1240 due to N(5+), and to the assignment of the following L doublets: λ990 to N(3+), λ1493 and 1744 to N(+), λ789 and λ658 to O(4+), and λ922 to O(2+). These results give us a new method of predicting spectra and of determining the state of ionization of atoms emitting certain lines. Doublet frequency differences in extreme ultra-violet for 2p2-2p1 terms due to B(3+) and C(4+) were measured by use of a special grating giving up to ten orders

The series spectra of the stripped atoms of phosphorus (PV), sulphur (SVI), and chlorine (ClVII)

Spectra of stripped atoms, sodium to chlorine.—Grating spectrograms of order three to eight have been obtained of the hot-spark spectra of these elements, which have yielded more accurate values for the (3p2-3p1), (3s-3p2) and (3p1-3d) terms of AlIII, SiIV, PV and SVI, and have enabled the identification and determination within about 5 frequency units (1) of 18 series lines of PV, and thence of the 14 most important term values (3s to 6f′′), (2) of 11 series lines of SVI, and 10 corresponding term values (3s to 5f′), and (3) of the first doublet of the principal series of ClVII at 800.70 and 813.00 A. The position of this doublet was first predicted by use of the method developed in a previous paper(1), based on observed regularities in these spectra. Further evidence is presented for the fact that both the regular and the irregular doublet laws of x-ray spectra, hold also throughout the field of optics. A plot of sqrt[ν/R] for the stripped atom levels as a function of atomic number gives approximately straight lines (Moseley law), those for the 3s, 3p and 3d terms and for the 4s, 4p, 4d and 4f terms being approximately parallel (irregular doublet law). The doublet separations d1d2, however, do not fit well into the relativity doublet law, the ratio of observed to theoretical values decreasing from about .8 for SVI to less than .2 for SiIV, while AlIII and MgII are anomalous, d1 having a greater frequency than d2. The general similarity of the spectra of all these elements is strikingly shown in spectrograms on which appear the "D" doublet of Na and the corresponding "D" doublets of the stripped atoms of Mg, Al, Si, P, S, and Cl in the second, third, fourth, fifth, sixth and seventh ordelrs, respectively, all near 5600 A, that for Na being farthest from the mean position. The frequencies of all the known terms found for the stripped atoms of Na to S, are collected in a table. Ionization potentials of PV and SiVI, computed from the 3s levels of PV and SVI, come out 64.7 and 87.6 volts

Non-linear optomechanical measurement of mechanical motion

Precision measurement of non-linear observables is an important goal in all facets of quantum optics. This allows measurement-based non-classical state preparation, which has been applied to great success in various physical systems, and provides a route for quantum information processing with otherwise linear interactions. In cavity optomechanics much progress has been made using linear interactions and measurement, but observation of non-linear mechanical degrees-of-freedom remains outstanding. Here we report the observation of displacement-squared thermal motion of a micro-mechanical resonator by exploiting the intrinsic non-linearity of the radiation pressure interaction. Using this measurement we generate bimodal mechanical states of motion with separations and feature sizes well below 100~pm. Future improvements to this approach will allow the preparation of quantum superposition states, which can be used to experimentally explore collapse models of the wavefunction and the potential for mechanical-resonator-based quantum information and metrology applications.Comment: 8 pages, 4 figures, extensive supplementary material available with published versio

Dedication of the Palomar Observatory and the Hale Telescope

The dedication of the Palomar Observatory, if it were being held in England, would be accompanied by brilliant pageantry both of the state, with its knights, heralds, pursuivants, kings at arms, admirals and captains, and of the church with its bishops, priests and deacons, crucifiers and choirs; and I am sure that we feel the quality of religion in this ceremony. We would hear the choirs chanting in antiphony that great canticle which so delights the choir boys: Benedicite, omnia opera Domini