A combined fit is presented to data onpp annihilation in flight to final states ηπ 0 π 0 , π 0 π 0 , ηη, ηη and π − π + . The emphasis lies in improving an earlier study of ηπ 0 π 0 by fitting data at ninep momenta simultaneously and with parameters consistent with the two-body channels. There is evidence for all of the I = 0, C = +1qq states expected in this mass range. New resonances are reported with masses and widths (M, Γ) as follows: J PC = 4 −+ (2328 ± 38, Γ = 240 ± 90) MeV, 1 ++ (1971 ± 15, 240 ± 45) MeV, 0 −+ (2285 ± 20, 325 ± 30) MeV, and 0 −+ (2010 +35 −60 , 270 ± 60) MeV. Errors on the masses and widths of other resonances are also reduced substantially. All states lie close to parallel straight line trajectories of excitation number v. mass squared.

We have measured the photoabsorption spectra of Pb II and Bi III in the wavelength range between 37 and 70 nm. A number of features in the spectra have been identified with the aid of the Cowan suite of atomic codes. 5d → 6p transitions from the ground configuration (5d106s26p) and three excited configurations (5d106s26d, 5d106s27s, 5d106s6p2) give rise to the most prominent features in the measured spectra. Evidence of excited states including (5d106s6p2 (4P3/2, 4D3/2)) for Pb II and (5d106s6p2 (4P1/2, 4P3/2)) for Bi III was observed in our measurements.

In this work we report soft x-ray (SXR) photoabsorption measurements in neutral methane and carbon dioxide molecules and their corresponding photoionized plasmas. The SXR radiation was generated by a table-top laser produced plasma source based on a double stream gas puff target. At low SXR intensities only features related to neutral molecules are present in the absorption spectrum. On the other hand, as the radiation intensity increases, we observe new absorption features in the low photon energy side of the spectrum. In that case fragments such as neutral and ionized molecules, atoms and atomic ions are found to contribute to the absorption spectrum of the plasmas. To our knowledge these are the first measurements where this laser plasma based SXR source is used to both create and probe a molecular plasma. Emphasis is placed on identifying the fragment species and the corresponding transitions.

Functional materials with sphalerite-type crysta l structures, like GaAs, InP or CdTe, are subject of continuous intense research because of their importance in electronic device applications. Fundamental transmission electron microscopy studies of defects and of interfaces in bulk crystals or in epitaxial layers apply predominantly <110> (<001>)-zone-axis investigations of cross-section (plan-view) samples prepared from {001}-oriented substrate materials. A complete characterization of defects (e.g. the discrimination between-and-dislocations) and of interfaces require the analysis of the polar arrangement of the crystal atoms. Recently, we could show that the dynamical contrast of high odd-index bend contours in (-200) and (200) dark-field images of <001> plan-view crystal samples can be exploited for the polarity determination, without the need for a comparison with dynamical contrast simulations [1]. Moreover, we proposed a general contrast rule applicable both to Bragg-lines in convergent-beam electron diffraction (CBED) patterns and to bend contours in conventional TEM images which facilitates a unified analysis of the polarity of sphalerite-type crystals both for <001> and for <110> sample geometry [1,2]. This approach complements the CBED method used by Taftø and Spence [3] who determined the polarity for <110> cross-section samples of GaAs (and other compounds with small differences of the atomic number Z of the constituting atoms) by comparing the dynamical contrast of high odd-index Bragg-lines of type {119} and {1,1,11} in the (002) and (00-2) dark-field discs. Our contrast rules state that high-index Bragg-lines hkl with h+k+l = 4m+1 appear with negative (dark) contrast in a CBED disc of type {002} while the 'symmetrical' Bragglines-h-k 2-l (index sum = 4m+3) show bright or faded (at large differences of Z) contrast in the opposite disc {00-2}. The analyses use the convention that, within the cubic unit cell, the light atom is located at (0, 0, 0) and the heavy atom is placed at (¼, ¼, ¼). The optimum choice of reflections hkl and the accessible range of sample thicknesses depend on the material. As a rule of thumb, the reflections hkl and 002 should have similar structure factors, and the sample thickness should be small compared with the extinction distances but still large enough to reveal the dynamical contrast effects in the {002} discs [1]. For GaAs, GaP and GaSb, we have already confirmed the validity of the contrast rule for numerous Bragg-lines [1,2,4,5]. A more critical case is InP with its large atomic number difference. FIG 1 demonstrates by comparing experimental and simulated CBED patterns for InP that the polarity can be unambiguously determined both in <110> cross-section (top) and in <001> plan-view (bottom) samples by applying the contrast rule to Bragg-lines of type {115}, {117} and {351}, {551}, respectively, thus confirming convincingly the more general validity of the contrast rule.