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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Tm2(Ga3Ir)3 by Materials Project

Tm2(IrGa3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tm is bonded in a 11-coordinate geometry to eleven Ga atoms. There are a spread of Tm–Ga bond distances ranging from 2.99–3.15 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.56–2.66 Å. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.55–2.65 Å. There are four inequivalent Ga sites. In the first Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Tm, two equivalent Ir, and six Ga atoms. There are four shorter (2.73 Å) and two longer (2.75 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 3-coordinate geometry to three equivalent Tm, three Ir, and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.76–2.94 Å. In the third Ga site, Ga is bonded in a 3-coordinate geometry to two equivalent Tm, three Ir, and five Ga atoms. There are two shorter (2.79 Å) and one longer (2.82 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Tm, two equivalent Ir, and six Ga atoms. The Ga–Ga bond length is 2.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2(Ga3Ir)3 by Materials Project

Er2(IrGa3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Er is bonded in a 11-coordinate geometry to eleven Ga atoms. There are a spread of Er–Ga bond distances ranging from 3.00–3.15 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.57–2.66 Å. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.56–2.64 Å. There are four inequivalent Ga sites. In the first Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Er, two equivalent Ir, and six Ga atoms. There are four shorter (2.74 Å) and two longer (2.76 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 3-coordinate geometry to three equivalent Er, three Ir, and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.77–2.94 Å. In the third Ga site, Ga is bonded in a 3-coordinate geometry to two equivalent Er, three Ir, and five Ga atoms. There are two shorter (2.80 Å) and one longer (2.81 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Er, two equivalent Ir, and six Ga atoms. The Ga–Ga bond length is 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(SiIr)2 by Materials Project

Th(IrSi)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.19 Å) and four longer (3.29 Å) Th–Ir bond lengths. There are four shorter (3.21 Å) and four longer (3.23 Å) Th–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent Th and four equivalent Si atoms to form distorted IrTh4Si4 tetrahedra that share corners with twelve equivalent SiTh4Ir4 tetrahedra, edges with two equivalent SiTh4Ir4 tetrahedra, edges with four equivalent IrTh4Si4 tetrahedra, and faces with four equivalent IrTh4Si4 tetrahedra. All Ir–Si bond lengths are 2.47 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Th and five Si atoms. There are one shorter (2.42 Å) and four longer (2.45 Å) Ir–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Th and four equivalent Ir atoms to form distorted SiTh4Ir4 tetrahedra that share corners with twelve equivalent IrTh4Si4 tetrahedra, edges with two equivalent IrTh4Si4 tetrahedra, edges with four equivalent SiTh4Ir4 tetrahedra, and faces with four equivalent SiTh4Ir4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Th and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(GeIr)2 by Materials Project

PrIr2Ge2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.27 Å) and four longer (3.36 Å) Pr–Ir bond lengths. There are four shorter (3.28 Å) and four longer (3.31 Å) Pr–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Pr and five Ge atoms. There are one shorter (2.46 Å) and four longer (2.51 Å) Ir–Ge bond lengths. In the second Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.53 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Pr and five Ir atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Pr and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti6Al16Ir7 by Materials Project

Ti6Ir7Al16 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ti is bonded in a 4-coordinate geometry to four equivalent Ti, four equivalent Ir, and eight Al atoms. All Ti–Ti bond lengths are 3.08 Å. All Ti–Ir bond lengths are 3.16 Å. There are four shorter (2.71 Å) and four longer (3.20 Å) Ti–Al bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent Ti and eight Al atoms. There are four shorter (2.49 Å) and four longer (2.66 Å) Ir–Al bond lengths. In the second Ir site, Ir is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Ir–Al bond lengths are 2.54 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 3-coordinate geometry to three equivalent Ti and three equivalent Ir atoms. In the second Al site, Al is bonded to three equivalent Ti and four Ir atoms to form a mixture of distorted face, edge, and corner-sharing AlTi3Ir4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Dy5(Ge5Ir2)2 by Materials Project

Dy5(Ir2Ge5)2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are three inequivalent Dy sites. In the first Dy site, Dy is bonded in a 8-coordinate geometry to four equivalent Ir and twelve Ge atoms. All Dy–Ir bond lengths are 3.22 Å. There are eight shorter (2.99 Å) and four longer (3.36 Å) Dy–Ge bond lengths. In the second Dy site, Dy is bonded to four equivalent Ir and eight Ge atoms to form face-sharing DyGe8Ir4 cuboctahedra. All Dy–Ir bond lengths are 3.13 Å. There are a spread of Dy–Ge bond distances ranging from 2.94–3.09 Å. In the third Dy site, Dy is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Dy–Ir bond lengths are 3.34 Å. There are a spread of Dy–Ge bond distances ranging from 3.29–3.38 Å. Ir is bonded in a 10-coordinate geometry to five Dy and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.47–2.58 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to six Dy, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.46 Å. In the second Ge site, Ge is bonded in a 2-coordinate geometry to five Dy, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.54 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to four Dy, two equivalent Ir, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.90 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2(Al3Ir)3 by Materials Project

Pr2(IrAl3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Pr is bonded in a 11-coordinate geometry to eleven Al atoms. There are a spread of Pr–Al bond distances ranging from 3.10–3.19 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Al atoms. There are a spread of Ir–Al bond distances ranging from 2.61–2.64 Å. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Al atoms. There are a spread of Ir–Al bond distances ranging from 2.61–2.63 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Pr, two equivalent Ir, and six Al atoms. There are two shorter (2.75 Å) and four longer (2.79 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 3-coordinate geometry to three equivalent Pr, three Ir, and one Al atom. In the third Al site, Al is bonded in a 3-coordinate geometry to two equivalent Pr and three Ir atoms. In the fourth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Pr, two equivalent Ir, and one Al atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd(GeIr)2 by Materials Project

Nd(IrGe)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Nd is bonded in a 12-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.25 Å) and four longer (3.39 Å) Nd–Ir bond lengths. There are four shorter (3.27 Å) and four longer (3.29 Å) Nd–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Nd and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.53 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Nd and five Ge atoms. There are one shorter (2.46 Å) and four longer (2.50 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Nd and four equivalent Ir atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Nd and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(SiIr)2 by Materials Project

Ho(IrSi)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight Ir and eight Si atoms. There are four shorter (3.13 Å) and four longer (3.25 Å) Ho–Ir bond lengths. There are four shorter (3.16 Å) and four longer (3.18 Å) Ho–Si bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent Ho and four equivalent Si atoms to form distorted IrHo4Si4 tetrahedra that share corners with twelve equivalent SiHo4Ir4 tetrahedra, edges with two equivalent SiHo4Ir4 tetrahedra, edges with four equivalent IrHo4Si4 tetrahedra, and faces with four equivalent IrHo4Si4 tetrahedra. All Ir–Si bond lengths are 2.43 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Ho and five Si atoms. There are one shorter (2.37 Å) and four longer (2.42 Å) Ir–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Ho and four equivalent Ir atoms to form distorted SiHo4Ir4 tetrahedra that share corners with twelve equivalent IrHo4Si4 tetrahedra, edges with two equivalent IrHo4Si4 tetrahedra, edges with four equivalent SiHo4Ir4 tetrahedra, and faces with four equivalent SiHo4Ir4 tetrahedra. In the second Si site, Si is bonded in a 9-coordinate geometry to four equivalent Ho and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr6Al16Ir7 by Materials Project

Zr6Ir7Al16 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Zr is bonded in a 4-coordinate geometry to four equivalent Ir and eight Al atoms. All Zr–Ir bond lengths are 3.18 Å. There are four shorter (2.85 Å) and four longer (3.15 Å) Zr–Al bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to four equivalent Zr and eight Al atoms to form distorted IrZr4Al8 cuboctahedra that share corners with four equivalent IrZr4Al8 cuboctahedra, corners with eight equivalent AlZr3Ir4 tetrahedra, edges with four equivalent AlZr3Ir4 tetrahedra, and faces with eight equivalent IrZr4Al8 cuboctahedra. There are four shorter (2.53 Å) and four longer (2.72 Å) Ir–Al bond lengths. In the second Ir site, Ir is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Ir–Al bond lengths are 2.57 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 3-coordinate geometry to three equivalent Zr and three equivalent Ir atoms. In the second Al site, Al is bonded to three equivalent Zr and four Ir atoms to form distorted AlZr3Ir4 tetrahedra that share corners with six equivalent IrZr4Al8 cuboctahedra, corners with seven equivalent AlZr3Ir4 tetrahedra, edges with three equivalent IrZr4Al8 cuboctahedra, edges with three equivalent AlZr3Ir4 tetrahedra, and faces with three equivalent AlZr3Ir4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm2(Ga3Ir)3 by Materials Project

Sm2(IrGa3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Sm is bonded in a 11-coordinate geometry to eleven Ga atoms. There are a spread of Sm–Ga bond distances ranging from 3.04–3.18 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.60–2.66 Å. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.59–2.65 Å. There are four inequivalent Ga sites. In the first Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Sm, two equivalent Ir, and six Ga atoms. There are two shorter (2.75 Å) and four longer (2.76 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 3-coordinate geometry to three equivalent Sm, three Ir, and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.79–2.96 Å. In the third Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Sm, three Ir, and five Ga atoms. There are one shorter (2.80 Å) and two longer (2.84 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Sm, two equivalent Ir, and six Ga atoms. The Ga–Ga bond length is 2.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2(Ga3Ir)3 by Materials Project

Ho2(IrGa3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ho is bonded in a 11-coordinate geometry to eleven Ga atoms. There are a spread of Ho–Ga bond distances ranging from 3.01–3.16 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.58–2.66 Å. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Ga atoms. There are a spread of Ir–Ga bond distances ranging from 2.56–2.65 Å. There are four inequivalent Ga sites. In the first Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Ho, two equivalent Ir, and six Ga atoms. There are four shorter (2.75 Å) and two longer (2.76 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 3-coordinate geometry to three equivalent Ho, three Ir, and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.78–2.95 Å. In the third Ga site, Ga is bonded in a 3-coordinate geometry to two equivalent Ho, three Ir, and five Ga atoms. There are one shorter (2.81 Å) and two longer (2.82 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Ho, two equivalent Ir, and six Ga atoms. The Ga–Ga bond length is 2.74 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(GeIr)2 by Materials Project

Th(IrGe)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.26 Å) and four longer (3.35 Å) Th–Ir bond lengths. There are four shorter (3.26 Å) and four longer (3.30 Å) Th–Ge bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.53 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Th and five Ge atoms. There are one shorter (2.44 Å) and four longer (2.51 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Ir atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Th and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi4Ir by Materials Project

IrBi4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Bi atoms. There are a spread of Ir–Bi bond distances ranging from 2.85–2.89 Å. In the second Ir site, Ir is bonded in a body-centered cubic geometry to eight Bi atoms. There are four shorter (2.88 Å) and four longer (2.90 Å) Ir–Bi bond lengths. There are four inequivalent Bi sites. In the first Bi site, Bi is bonded in a distorted water-like geometry to two Ir atoms. In the second Bi site, Bi is bonded in a distorted water-like geometry to two Ir atoms. In the third Bi site, Bi is bonded in a distorted water-like geometry to two equivalent Ir atoms. In the fourth Bi site, Bi is bonded in a distorted water-like geometry to two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tb2(Al3Ir)3 by Materials Project

Tb2(IrAl3)3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to eleven Al atoms. There are a spread of Tb–Al bond distances ranging from 3.05–3.15 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Al atoms. There are four shorter (2.57 Å) and four longer (2.62 Å) Ir–Al bond lengths. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight Al atoms. There are a spread of Ir–Al bond distances ranging from 2.56–2.61 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tb and two equivalent Ir atoms. In the second Al site, Al is bonded in a 3-coordinate geometry to three equivalent Tb, three Ir, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 3-coordinate geometry to two equivalent Tb, three Ir, and five Al atoms. There are one shorter (2.72 Å) and two longer (2.87 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tb, two equivalent Ir, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2001

Optical metrology for testing an all-composite 2-meter diameter mirror

The Herschel Space Observatory (formerly known as FIRST) consists of a 3.5 m space telescope designed for use in the long IR and sub-milimeter wavebands. To demonstrate the viability of a carbon fiber composite telescope for this application, Composite Optics Incorporated (COI) manufactured a fast (f/1), large (2 m), lightweight (10.1 kg/m squared) demonstration mirror. A key challenge in demonstrating the performance of this novel mirror was to characterize the surface accuracy at cryogenic (70 K) temperatures. A wide variety of optical metrology techniques were investigated and a brief survey of empirical test results and limitations of the various techniques will be presented in this paper. Two complementary infrared (IR)techniques operating at a wavelength of 10.6 microns were chosen for further development: (1) IR Twyman-Green Phase Shifting Interferometry (IR PSI) and (2) IR Shack-Hartmann (IR SH) Wavefront Sensing. Innovative design modifications made to an existing IR PSI to achieve high-resolution, scannable, infrared measurements of the composite mirror are described. The modified interferometer was capable of measuring surface gradients larger than 350 microradians. The design and results of measurements made with a custom-built IR SH Wavefrong Sensor operating at 10.6 microns are also presented. A compact experimental setup permitting simultaneous operation of both the IR PSI and IR SH tools is shown. The advantages and the limitations of the two key IR metrology tools are discussed.

IR metrology phase shifting interferometry Shack-H↗
DOE OSTI2021

How much information on precipitation is contained in satellite infrared imagery?

Satellite infrared (IR) brightness temperature providing information on the characteristics of cloud tops is one of the primary input data used for estimating precipitation from satellites. Thus, the natural questions to ask are: Does IR imagery contain more information about precipitation in some regions more than others? What are the factors that lead to such differences? Should we expect the amount of information provided by IR imagery to change with respect to temporal or spatial aggregation? Comprehensive analysis of the accuracy of satellite-based precipitation estimates obtained from any given algorithm may provide qualitative answers to the above questions. However, such an approach only offers conclusions within the limited context of the algorithm used to obtain precipitation estimates; that is, patterns caused by the inherent information content of IR imagery are inextricable from those induced by assumptions embedded in the precipitation estimation algorithm. Here, we address the abovementioned questions from a different perspective using an information-theoretic measure, free of structural assumptions and general to a wide range of relationships, to characterize the average and seasonal dependence between IR imagery provided by satellite sensors in the spectral range (10.7–11.5 μm) and precipitation rates in the contiguous United States (CONUS) across distinct temporal and spatial scales. We analyze a total of more than 1.3 billion pairs of IR and precipitation observations over CONUS, and we observe interesting patterns. First, we show that there is a strong inverse relationship (ρ = - 0.73) between the information content of IR data and the number of no-rain observations; however, its robustness varies regionally and seasonally with less significant correlation during the warm season. Second, we demonstrate that the intuitive relationship of increasing dependence between IR and precipitation as a result of temporal or spatial aggregation exhibits a diminishing returns behavior. For instance, temporal aggregation from 1 to 3 h increases the dependence approximately 7 times as much as temporal aggregation from 12 to 24 h. Furthermore, we quantitatively examine and re-confirm several statements previously reported in the literature such as the strong association between IR and precipitation in convective storms and the low association in orographic rainfall. Finally, we conclude by illustrating the potential of the analysis in diagnosis of operational algorithms for estimating precipitation from IR brightness temperature. The findings of this study pinpoint spatial domains and time scales at which IR is not an adequate proxy for estimating precipitation. Thus, they can potentially guide the development of operational algorithms that utilize satellite Infrared imagery for estimating, downscaling and data fusion of precipitation. Finally, the analysis presented here opens up the possibility of developing new methodologies for diagnosis of satellite-based precipitation estimation algorithms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Reactivity of Iridium Complexes of a Triphosphorus-Pincer Ligand Based on a Secondary Phosphine. Catalytic Alkane Dehydrogenation and the Origin of Extremely High Activity

The selective functionalization of alkanes and alkyl groups is a major goal of chemical catalysis. Toward this end, a bulky triphosphine with a central secondary phosphino group, bis(2-di-t-butyl-phosphinophenyl)phosphine ( tBu P H PP), has been synthesized. When complexed to iridium, it adopts a meridional (“pincer”) configuration. The secondary phosphino H atom can undergo migration to iridium to give an anionic phosphido-based–pincer ( tBu PPP) complex. Stoichiometric reactions of the ( tBu PPP)Ir complexes reflect a distribution of steric bulk around the iridium center in which the coordination site trans to the phosphido group is quite crowded; one coordination site cis to the phosphido is even more crowded; and the remaining site is particularly open. The ( tBu PPP)Ir precursors are the most active catalysts reported to date for dehydrogenation of n-alkanes, by about 2 orders of magnitude. The electronic properties of the iridium center are similar to that of well-known analogous ( R PCP)Ir catalysts. Accordingly, DFT calculations predict that ( tBu PPP)Ir and ( tBu PCP)Ir are, intrinsically, comparably active for alkane dehydrogenation. While dehydrogenation by ( R PCP)Ir proceeds through an intermediate trans-(PCP)IrH 2 (alkene), ( tBu PPP)Ir follows a pathway proceeding via cis-(PPP)IrH 2 (alkene), thereby circumventing unfavorable placement of the alkene at the bulky site trans to phosphorus. ( tBu PPP)Ir and ( tBu PCP)Ir, however, have analogous resting states: square planar (pincer)Ir(alkene). Alkene coordination at the crowded trans site is therefore unavoidable in the resting states. Furthermore, the resting state of the ( tBu PPP)Ir catalyst is destabilized by the architecture of the ligand, and this is largely responsible for its unusually high catalytic activity.

02 PETROLEUM↗