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TPSAS-NF1676L-14096-DND

This technology development was initiated during NASA Earth Science Technology Office (ESTO) funded Laser Risk Reduction Program (LRRP) with the objective to develop a Thulium (Tm) fiber laser pumped Holmium (Ho) solid-state laser that generates laser pulses in the 2?m wavelength for pulsed CO2 DIAL/IPDA instrument. The key performance characteristics of this laser, such as energy, pulse repetition rate, pulse width, efficiency, frequency accuracy and stability, will meet or exceed the needs of the NASA Active Sensing of CO2 Emissions over Night, Days, and Seasons (ASCENDS) transmitter as currently envisioned. This space qualifiable laser architecture utilizes fiber laser and solid-state crystal laser technologies. One of the outstanding properties of the fiber laser is its efficiency. However, it inherently has low damage threshold at high energy pulses. On the other hand, the solid state laser has the capability to produce Joule-level energy at 2?m wavelength. The proposed laser combines the advantages of both lasers to provide the desired energy with high efficiency.

Upendra N Singh↗
DOE OSTI2020

Materials Data on Ho9Er3(MnBi2)2 by Materials Project

Er3Ho9(MnBi2)2 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are three inequivalent Er sites. In the first Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.23 Å. All Er–Bi bond lengths are 3.32 Å. In the second Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.23 Å. All Er–Bi bond lengths are 3.32 Å. In the third Er site, Er is bonded in a 5-coordinate geometry to one Mn and four equivalent Bi atoms. The Er–Mn bond length is 3.23 Å. All Er–Bi bond lengths are 3.32 Å. There are nine inequivalent Ho sites. In the first Ho site, Ho is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Ho–Mn bond length is 3.23 Å. All Ho–Bi bond lengths are 3.32 Å. In the second Ho site, Ho is bonded in a 5-coordinate geometry to one Mn and four equivalent Bi atoms. The Ho–Mn bond length is 3.23 Å. All Ho–Bi bond lengths are 3.32 Å. In the third Ho site, Ho is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Ho–Mn bond length is 3.24 Å. All Ho–Bi bond lengths are 3.32 Å. In the fourth Ho site, Ho is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Ho–Mn bond lengths are 2.88 Å. There are one shorter (3.23 Å) and one longer (3.24 Å) Ho–Bi bond lengths. In the fifth Ho site, Ho is bonded to two equivalent Mn and two Bi atoms to form a mixture of distorted edge and corner-sharing HoMn2Bi2 tetrahedra. Both Ho–Mn bond lengths are 2.88 Å. Both Ho–Bi bond lengths are 3.24 Å. In the sixth Ho site, Ho is bonded to two equivalent Mn and two equivalent Bi atoms to form a mixture of distorted edge and corner-sharing HoMn2Bi2 tetrahedra. Both Ho–Mn bond lengths are 2.88 Å. Both Ho–Bi bond lengths are 3.24 Å. In the seventh Ho site, Ho is bonded to two equivalent Mn and two Bi atoms to form a mixture of distorted edge and corner-sharing HoMn2Bi2 tetrahedra. Both Ho–Mn bond lengths are 2.88 Å. Both Ho–Bi bond lengths are 3.24 Å. In the eighth Ho site, Ho is bonded to two equivalent Mn and two equivalent Bi atoms to form a mixture of distorted edge and corner-sharing HoMn2Bi2 tetrahedra. Both Ho–Mn bond lengths are 2.88 Å. Both Ho–Bi bond lengths are 3.24 Å. In the ninth Ho site, Ho is bonded to two equivalent Mn and two Bi atoms to form a mixture of distorted edge and corner-sharing HoMn2Bi2 tetrahedra. Both Ho–Mn bond lengths are 2.88 Å. Both Ho–Bi bond lengths are 3.24 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 9-coordinate geometry to two Er and seven Ho atoms. In the second Mn site, Mn is bonded in a 9-coordinate geometry to one Er and eight Ho atoms. There are three inequivalent Bi sites. In the first Bi site, Bi is bonded in a 9-coordinate geometry to four Er and five Ho atoms. In the second Bi site, Bi is bonded in a 9-coordinate geometry to two equivalent Er and seven Ho atoms. In the third Bi site, Bi is bonded in a 9-coordinate geometry to two equivalent Er and seven Ho atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoAl3(PbO4)2 by Materials Project

HoAl3(PbO4)2 is Esseneite-like structured and crystallizes in the cubic Pn-3m space group. The structure is three-dimensional. Ho3+ is bonded to eight O2- atoms to form HoO8 hexagonal bipyramids that share edges with six equivalent AlO4 tetrahedra. There are two shorter (2.26 Å) and six longer (2.55 Å) Ho–O bond lengths. Al3+ is bonded to four equivalent O2- atoms to form distorted AlO4 tetrahedra that share corners with four equivalent AlO4 tetrahedra and edges with two equivalent HoO8 hexagonal bipyramids. All Al–O bond lengths are 1.75 Å. Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.37 Å) and three longer (3.13 Å) Pb–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ho3+ and three equivalent Pb2+ atoms to form a mixture of distorted corner and edge-sharing OHoPb3 tetrahedra. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+, two equivalent Al3+, and one Pb2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Crystal and magnetic structure of polar oxide HoCrWO 6

In this study, polar magnetic oxide HoCrWO 6 is synthesized and its crystal structure, magnetic structure, and thermodynamic properties are investigated. HoCrWO 6 forms the polar crystal structure (space group Pna 2 1 (#33)) due to the cation ordering of W 6+ and Cr 3+ . There is an antiferromagnetic transition at T N = 24.5 K along with the magnetic entropy change (~5 J.Kg. –1 K –1 at 70 kOe). Neutron diffraction measurement indicates that both Cr and Ho sublattices are ordered with the moment of 2.32(5)μ B and 8.7(4)μ B at 2 K, respectively. While Cr forms A-type collinear antiferromagnetic (AFM) structure with magnetic moment along the b axis, Ho sublattice orders in a non-coplanar AFM arrangement. A comparison with isostructural DyFeWO 6 and DyCrWO 6 indicates that the magnetic structure of this family of compounds is controlled by the presence or absence of e g electrons in the transition metal sublattice.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Sr2HoCu2(BiO4)2 by Materials Project

Sr2HoCu2(BiO4)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.59–2.78 Å. Ho3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ho–O bond lengths are 2.39 Å. Cu+1.50+ is bonded to five O2- atoms to form distorted CuO5 square pyramids that share a cornercorner with one BiO6 octahedra and corners with four equivalent CuO5 square pyramids. The corner-sharing octahedral tilt angles are 0°. There are four shorter (1.89 Å) and one longer (2.57 Å) Cu–O bond lengths. Bi3+ is bonded to six O2- atoms to form distorted BiO6 octahedra that share corners with four equivalent BiO6 octahedra, a cornercorner with one CuO5 square pyramid, and edges with eight equivalent BiO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are a spread of Bi–O bond distances ranging from 2.13–2.94 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent Sr2+, two equivalent Ho3+, and two equivalent Cu+1.50+ atoms. In the second O2- site, O2- is bonded to one Sr2+ and five equivalent Bi3+ atoms to form a mixture of edge and corner-sharing OSrBi5 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Sr2+, one Cu+1.50+, and one Bi3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHo(CO3)2 by Materials Project

KHo(CO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.80–3.40 Å. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.48 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.28–1.32 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent K1+, one Ho3+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+, one Ho3+, and one C4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ho3+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3Ho(PO4)2 by Materials Project

Na3Ho(PO4)2 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.92 Å. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.91 Å. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.57 Å. In the fourth Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.87 Å. In the fifth Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.95 Å. In the sixth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.60 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.25–2.53 Å. In the second Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.26–2.53 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the third P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. In the fourth P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four Na1+, one Ho3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four Na1+, one Ho3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ho3+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ho3+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Ho3+, and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoUTe6 by Materials Project

UHoTe6 crystallizes in the orthorhombic Amm2 space group. The structure is two-dimensional and consists of two UHoTe6 sheets oriented in the (0, 1, 0) direction. U3+ is bonded in a 9-coordinate geometry to nine Te1- atoms. There are a spread of U–Te bond distances ranging from 3.16–3.24 Å. Ho3+ is bonded in a 9-coordinate geometry to nine Te1- atoms. There are six shorter (3.25 Å) and three longer (3.27 Å) Ho–Te bond lengths. There are six inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent U3+ and four equivalent Te1- atoms. All Te–Te bond lengths are 3.09 Å. In the second Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Ho3+ and four equivalent Te1- atoms. All Te–Te bond lengths are 3.09 Å. In the third Te1- site, Te1- is bonded in a 5-coordinate geometry to one U3+ and four equivalent Ho3+ atoms. In the fourth Te1- site, Te1- is bonded in a 5-coordinate geometry to four equivalent U3+ and one Ho3+ atom. In the fifth Te1- site, Te1- is bonded in a 6-coordinate geometry to two equivalent Ho3+ and four equivalent Te1- atoms. In the sixth Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent U3+ and four equivalent Te1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3Er9(MnBi2)2 by Materials Project

Er9Ho3(MnBi2)2 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are nine inequivalent Er sites. In the first Er site, Er is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Er–Mn bond lengths are 2.87 Å. There are one shorter (3.23 Å) and one longer (3.24 Å) Er–Bi bond lengths. In the second Er site, Er is bonded to two equivalent Mn and two Bi atoms to form distorted corner-sharing ErMn2Bi2 tetrahedra. Both Er–Mn bond lengths are 2.87 Å. Both Er–Bi bond lengths are 3.23 Å. In the third Er site, Er is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Er–Mn bond lengths are 2.87 Å. There are one shorter (3.23 Å) and one longer (3.24 Å) Er–Bi bond lengths. In the fourth Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.22 Å. All Er–Bi bond lengths are 3.32 Å. In the fifth Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.22 Å. All Er–Bi bond lengths are 3.32 Å. In the sixth Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.23 Å. There are two shorter (3.31 Å) and two longer (3.32 Å) Er–Bi bond lengths. In the seventh Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.22 Å. There are two shorter (3.31 Å) and two longer (3.32 Å) Er–Bi bond lengths. In the eighth Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.23 Å. There are two shorter (3.31 Å) and two longer (3.32 Å) Er–Bi bond lengths. In the ninth Er site, Er is bonded in a 5-coordinate geometry to one Mn and four Bi atoms. The Er–Mn bond length is 3.23 Å. There are two shorter (3.31 Å) and two longer (3.32 Å) Er–Bi bond lengths. There are three inequivalent Ho sites. In the first Ho site, Ho is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Ho–Mn bond lengths are 2.87 Å. Both Ho–Bi bond lengths are 3.24 Å. In the second Ho site, Ho is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Ho–Mn bond lengths are 2.87 Å. Both Ho–Bi bond lengths are 3.24 Å. In the third Ho site, Ho is bonded in a 4-coordinate geometry to two equivalent Mn and two Bi atoms. Both Ho–Mn bond lengths are 2.87 Å. Both Ho–Bi bond lengths are 3.24 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 9-coordinate geometry to seven Er and two equivalent Ho atoms. In the second Mn site, Mn is bonded in a 9-coordinate geometry to five Er and four Ho atoms. There are four inequivalent Bi sites. In the first Bi site, Bi is bonded in a 9-coordinate geometry to seven Er and two Ho atoms. In the second Bi site, Bi is bonded in a 9-coordinate geometry to eight Er and one Ho atom. In the third Bi site, Bi is bonded in a 9-coordinate geometry to seven Er and two Ho atoms. In the fourth Bi site, Bi is bonded in a 9-coordinate geometry to eight Er and one Ho atom.

36 MATERIALS SCIENCE↗
NASA NTRS2002

D-Wave Resonances in Positronium Hydride

The problem of calculating the position and width of the lowest-lying (L = 0, 1) resonances in the Ps + H scattering system has recently been re-examined by the authors [1]. In the model used, resonances axe assumed generated by bound Rydberg states in the closed re-arranged channel [e(+) + H(-)]. This infinite series of Coulomb bound states are shifted somewhat by the coupling with the open scattering channel [Ps + H]. Estimates using this approach, first carried out by one of the authors [2] using a simple form of scattering wavefunction, indicated an anticipated small shift of resonance away from the Rydberg energy in the S-wave (L = 0). More recent results by Ho and Yan [3] using the complex-rotation method showed unexpected significant shifting in the P (L = 1) and D (L = 2)-wave resonance energies from their respective unperturbed values. Our re-calculation of the resonances [I I for L = 0 and I indicates that, in each case, reasonably consistent resonance energies are obtained by coupling the two lowest lying states (IS and 2S for L = 0 and 2P and 3P for L = 1). For each L it is the higher state (2S and 3P, respectively) that produces the resonance. The lower state (1S and 2P, respectively) is effective only in increasing the non-resonant phase shift. In this work we extend the model to L = 2 (D-waves). Our results show that, unlike the S and P-waves, the 313-state alone produces a resonant energy that is very close to the result of Yan and Ho [3]. Inclusion of the 4D-state produces a second resonance in the scattering system shifted up slightly from its unperturbed Rydberg energy.

Drachman, Richard J.↗
NASA NTRS1995

The middle atmospheric response to short and long term solar UV variations: analysis of observations and 2D model results

We have investigated the middle atmospheric response to the 27-day and 11-yr solar UV flux variations at low to middle latitudes using a two-dimensional photochemical model. The model reproduced most features of the observed 27-day sensitivity and phase lag of the profile ozone response in the upper stratosphere and lower mesosphere, with a maximum sensitivity of +0.51% per 1% change in 205 nm flux. The model also reproduced the observed transition to a negative phase lag above 2 mb, reflecting the increasing importance with height of the solar modulated HO(x) chemistry on the ozone response above 45 km. The model revealed the general anti-correlation of ozone and solar UV at 65-75 km, and simulated strong UV responses of water vapor and HO(x) species in the mesosphere. Consistent with previous 1D model studies, the observed upper mesospheric positive ozone response averaged over +/- 40 was simulated only when the model water vapor concentrations above 75 km were significantly reduced relative to current observations. In agreement with observations, the model computed a low to middle latitude total ozone phase lag of +3 days and a sensitivity of +0.077% per 1% change in 205 nm flux for the 27-day solar variation, and a total ozone sensitivity of +0.27% for the 11-yr solar cycle. This factor of 3 sensitivity difference is indicative of the photochemical time constant for ozone in the lower stratosphere which is comparable to the 27-day solar rotation period but is much shorter than the 11-yr solar cycle.

Fleming, Eric L.↗
DOE OSTI2025

CMI Winter Meeting 2025 Presentation

Lanthanides are important to many technologies including magnets used in high efficiency traction motors. While common in the environment and industrial waste streams, lanthanides are often present at very low concentrations. This work demonstrates synergistic lanthanide recovery from an aqueous magnet leachate to single ppm concentrations using Na2SO4 addition and subsequent DME-FC treatment. It was found that combining DME-FC with low concentrations of Na2SO4 (~0.1 M) results in synergistic isolation of lanthanides while making use of Na2SO4, an excessive byproduct of hydrometallurgical metal production. Combined Na2SO4 + DME reduced lanthanide metal ion's (Pr, Nd, Sm, Gd, Dy, and Ho) solubilities by 1,000 - 25,000x with final concentrations ranging from 2 ppm to 200 ppm. This can be compared to 0.1 M Na2SO4 alone providing a 10 - 200x reduction and DME providing a 100 - 1,500x reduction in lanthanide solubilities. Final solution concentrations of lanthanides were 99.8% lower than what could not be achieved with either individual process. The results also reveal different periodic trends in the solubility reduction for DME and Na2SO4.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2020

Materials Data on RbHo2Cl7 by Materials Project

RbHo2Cl7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Rb1+ is bonded in a 10-coordinate geometry to ten Cl1- atoms. There are a spread of Rb–Cl bond distances ranging from 3.50–3.71 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted edge and face-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.69–2.79 Å. In the second Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted edge and face-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.69–2.73 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Rb1+ and two Ho3+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted L-shaped geometry to one Rb1+ and two Ho3+ atoms. In the third Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to one Rb1+ and two Ho3+ atoms. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Rb1+ and two Ho3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsHo2Cl7 by Materials Project

CsHo2Cl7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Cs1+ is bonded in a 10-coordinate geometry to ten Cl1- atoms. There are a spread of Cs–Cl bond distances ranging from 3.58–3.82 Å. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted edge and face-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.70–2.79 Å. In the second Ho3+ site, Ho3+ is bonded to seven Cl1- atoms to form a mixture of distorted edge and face-sharing HoCl7 pentagonal bipyramids. There are a spread of Ho–Cl bond distances ranging from 2.70–2.74 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Cs1+ and two Ho3+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted L-shaped geometry to one Cs1+ and two Ho3+ atoms. In the third Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to one Cs1+ and two Ho3+ atoms. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Cs1+ and two Ho3+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Simultaneous, in situ measurements of OH, HO2, O3, and H2O - A test of modeled stratospheric HO(x) chemistry

Simultaneous, in situ measurements of OH, HO2, H2O, and O3 from 37-23 km are reported. The partitioning between OH and HO2 and the total HO(x) concentration are compared with expected steady-state values. The ratio of HO2 to OH varies from less than 2 at 36 km to more than 3 at 25 km; in the lower stratosphere this ratio is nearly a factor of two less than predicted. The data are used to calculate HO(x) production and loss rates. The measured HO(x) mixing ratio is consistent with production dominated by the reaction of O(1D) with H2O, and loss controlled by NOy below 28 km and HO(x) above 30 km. The steady-state concentration of H2O2 is inferred from the measured HO2 concentration and calculated photolysis rate. The maximum H2O2 mixing ratio (at 33 km) is predicted to be less than 0.2 ppb.

Wennberg, P. O.↗
NASA NTRS2009

Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

Bai, Yingxin↗
DOE OSTI2024

Atomistic Probing of Defect-Engineered 2H-MoTe 2 Monolayers

Point defects dictate various physical, chemical, and optoelectronic properties of two-dimensional (2D) materials, and therefore, a rudimentary understanding of the formation and spatial distribution of point defects is a key to advancement in 2D material-based nanotechnology. In this work, we performed the demonstration to directly probe the point defects in 2H-MoTe 2 monolayers that are tactically exposed to (i) 200 °C-vacuum-annealing and (ii) 532 nm-laser-illumination; and accordingly, we utilize a deep learning algorithm to classify and quantify the generated point defects. We discovered that tellurium-related defects are mainly generated in both 2H-MoTe 2 samples; but interestingly, 200 °C-vacuum-annealing and 532 nm-laser-illumination modulate a strong n-type and strong p-type 2H-MoTe 2 , respectively. While 200 °C-vacuum-annealing generates tellurium vacancies or tellurium adatoms, 532 nm-laser-illumination prompts oxygen atoms to be adsorbed/chemisorbed at tellurium vacancies, giving rise to the p-type characteristic. This work significantly advances the current understanding of point defect engineering in 2H-MoTe 2 monolayers and other 2D materials, which is critical for developing nanoscale devices with desired functionality.

2H-MoTe 2↗
DOE OSTI2020

Materials Data on Ca(HoS2)2 by Materials Project

Ca(HoS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are four shorter (2.80 Å) and four longer (3.05 Å) Ca–S bond lengths. Ho3+ is bonded to eight equivalent S2- atoms to form a mixture of distorted face, edge, and corner-sharing HoS8 hexagonal bipyramids. There are a spread of Ho–S bond distances ranging from 2.74–3.01 Å. S2- is bonded in a 6-coordinate geometry to two equivalent Ca2+ and four equivalent Ho3+ atoms.

36 MATERIALS SCIENCE↗