Nonplanar Ring Research Articles

Enhanced beam quality for medical applications at 6.45 μm by using a RISTRA ZGP OPO

A high-average power ZGP OPO with a nonplanar ring RISTRA cavity, pumped by a Ho3+:LLF MOPA is presented. A maximum pulse energy at 100 Hz repetition rate of 5.67 mJ at 6.45 μm with a M2 = 1.8 was achieved. The slope efficiency was 16% and the emission spectrum is shown. With a repetition rate of 200 Hz an average output power of 0.95 W at 6.45 μm was reached.

Synthesis and structure of expanded pyriporphyrins containing a dipyrrylpyridine unit

Expanded pyriporphyrins with five and ten nitrogens were prepared in 67% and 6.5% yield, respectively, by the reactions of bis(azafulvene) and dipyrrylpyridine. The minimum 17-membered non-aromatic macrocycle made of four pyrroles and one pyridine is highly non-planar in comparison with orangarin that contains a tripyrrole unit instead of a dipyrrylpyridine unit. This highly non-planar ring structure is basically unchanged in the complex with trifluoroacetic acid (TFA) where carboxylate anions are bound on both sides of the macrocyle plane by multiple hydrogen bondings. This monopyridine-tetrapyrrole hybrid macrocycle was able to act as a dianionic ligand for various metal ions including lanthanide ions. In contrast to the reported figure eight type X-ray structure of turcasarin that is a double sized macrocycle of orangarin, the pyridine-containing macrocycle analog of the same 34-membered ring size isolated in this study was found not to take a figure eight type conformation as evidenced by X-ray crystallography of the tetracation with TFA anions.

非平面环形腔激光器的强度噪声及其抑制

非平面环形腔激光器的强度噪声及其抑制

Generalized sensitivity factors for optical-axis perturbation in nonplanar ring resonators

By utilizing the generalized ray matrix for spherical mirror reflection, two new sensitivity factors are introduced considering the perturbation of the optical-axis caused by the radial and axial displacements of a spherical mirror in a nonplanar ring resonator. Based on this, a novel way for finding the location of the singular points of the sensitivity factors is presented. It is found that some nonplanar ring resonators with the effective modes may have the singular points of the sensitivity factors. The unsuitable regions for nonplanar ring resonators are also obtained from the perspective of the sensitivity factors.

(7R,8S,9S,12S)-1-Benzyloxy-13,14-didehydro-12-hydroxy-2,13-dimethoxy-N-methylmorphinane

In the title compound, C26H31NO4, a sinomenine derivative, the angle between the two aromatic rings is 53.34 (4)°. The N-containing ring is in a chair conformation, while the other two non-planar rings are in a half-boat conformation. In the crystal, mol­ecules are linked by O—H⋯N inter­actions into a C(8) chain along [100].

360 mW of single-mode output power at 946 nm from a ring laser based on a specially designed Porro prism

In this paper, a nonplanar ring laser operating at 946 nm has been proposed and demonstrated by using a specially designed Porro prism together with a commercially available corner cube prism. An Nd:YAG with a shape of scalene right triangle and an undoped YAG are thermally bonded to fabricate the novel composite Porro prism. A magnetic field providing the nonreciprocal Faraday rotation is applied to the corner cube prism, which gives flexibility in choosing magneto-optic materials. The operating principle of single-frequency operation for this ring laser is illustrated in detail. A maximum continuous output power of 360 mW was achieved when the laser operated stably on the single axial mode. 473 nm single-frequency operation with 6.7 mW has also been demonstrated by intracavity doubling with LiB3O5 crystal.

Frequency stabilization of a single-frequency Q-switched Tm:YAG laser by using injection seeding technique

A stable single-frequency Q-switched Tm:YAG laser was demonstrated. The laser was injection seeded by a monolithic nonplanar ring oscillator laser utilizing the ramp-hold-fire technique. The measurements of the output parameters were presented. This paper focused on investigation of the frequency stability of the injection-seeded laser, which was measured by optical heterodyne technique. A method used to restrict the frequency jitter of the laser was discussed. The fluctuation of the laser frequency was reduced from 2.36 MHz (rms) to 1.07 MHz (rms) in 1 h by optimizing the voltage of the piezoelectric translator.

High Internal Energies of Proposed Asphaltene Structures

Molecular structures proposed in the literature as representative of asphaltenes attempt to encompass the results of numerous experiments and quantum mechanics calculations. This work demonstrates that certain features of chemical bonding in proposed structures lead directly to high energies and thus low relative occurrence probabilities. Hartree–Fock, quantum density functional theory, and classical force field calculations indicate features such as nonplanar aromatic rings that occur in structures proposed recently in the literature. Energy differences for altered pendant group locations were compared using smaller molecules as a reference. Small changes to side-chain positions preserve the overall architecture of the proposed asphaltene molecules while decreasing repulsive forces and restoring planar aromatic rings. The resulting structures are more appropriate for pursuing molecular hypotheses about asphaltenes.

Modulation Transfer Spectroscopy of ${}^{127}I_{2}$ Hyperfine Structure at 561 nm

Hyperfine structures of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">127</sup> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> absorption transitions near 561 nm are observed via modulation transfer spectroscopy by a homemade Nd:YAG monolithic nonplanar ring laser with its second harmonic generation (SHG) using a single-pass PPMgO:LN crystal. The observed <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> transitions are assigned according to theoretical calculation results of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> B-X transition. Two Nd:YAG lasers are locked to the 15th component of the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">127</sup> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> P(58)22-1 transition, and the measured frequency stability of these lasers is 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> for a 1-s averaging time. Frequency shifts with changing iodine cell vapor pressure and pump power are measured by observing the heterodyne beat between two <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -stabilized lasers.

Analysis on the polarization property of the eigenmodes in a nonplanar ring resonator

Based on the theory of the Abeles matrix, the reflections from the multilayer dielectric mirrors in a nonplanar ring resonator are discussed in detail considering the imperfect layer thickness and the incident angle errors. The polarization of Gaussian beams in nonplanar ring resonators are analyzed by using a statistical method and the way to analyze the stability of a nonplanar ring resonator in the perspective of polarization is also presented. The results show that a nonlanar ring resonator with a finite mode size may not have the reasonable polarization performances sometimes; the eigenmodes might be right- and left-handed elliptically polarized instead of circularly polarized, and they also have different ellipticity and round trip losses, which are critical for a nonplanar ring resonator. These interesting findings are important to the cavity designs of ring resonators with a nonplanar structure.

Acetylene⋅⋅⋅Furan Trimer Formation at 0.37 K as a Model for Ultracold Aggregation of Non‐ and Weakly Polar Molecules

We have studied the aggregation process of (C(2)H(2))⋅⋅⋅furan trimers at ultracold temperatures (0.37 K) in helium nanodroplets. Computational sampling of the potential energy surface using the multiple-minima-hypersurface (MMH) approach yielded seven possible minimum structures, optimized at the MP2 level of theory with the cc-pVTZ and 6-311++G(d,p) basis sets. Experimentally, we could assign five transitions in the IR spectrum of acetylene-furan aggregates in the acetylene C-H(asym) stretch region between 3240 and 3300 cm(-1) to vibrational bands of the 2:1 acetylene-furan trimer. The transitions were assigned to three ring structures that all contain the T-shaped acetylene dimer as structural sub-motif. Two of the structures form a nonplanar ring involving a C-H(Ac) ⋅⋅⋅π(Fu) bond, the third is a nearly planar ring containing a C-H(Ac) ⋅⋅⋅O(Fu) bond. This assignment was corroborated by quantum mechanical/molecular dynamics (QM/MD) simulations mimicking in detail the aggregation process of precooled monomers. The simulations provided evidence for a transition from a higher level local minimum to the global minimum state over a small barrier during the aggregation process. The experimentally observed structures can be explained by a step-by-step aggregation of moieties pre-cooled to 0.37 K that are steered by intermediate and short-range electrostatic interactions. Thus, we are able to unravel a special aggregation mechanism which differs from aggregation of molecules with large dipole moments where this aggregation process is dominated by long range 1/r(3) dipole-dipole interaction ("electrostatic steering"). This mechanism is expected to be a general mechanism in ultracold chemistry.

Narrowband Er:YAG nonplanar ring oscillator at 1645 nm

We report 1645 nm narrowband operation of a monolithic Er:YAG nonplanar ring oscillator resonantly pumped at 1532 nm. Unidirectional cw power up to 0.5 W was obtained with a measured linewidth of 21 kHz.

Injection-locked single-frequency laser with an output power of 220 W

A solid-state laser system for the next generation of gravitational wave detectors with an output power of 220 W at the wavelength of 1064 nm is presented. Single-frequency operation of the laser was achieved by injection-locking of a high-power ring oscillator to an amplified non-planar ring oscillator (NPRO) following the Pound–Drever–Hall scheme. The high-power stage which features four longitudinally pumped Nd:YAG laser crystals as active media in a ring resonator configuration was designed for reliable long term operation. Using a non-confocal ring cavity to filter the output beam, a pure TEM00 mode with 168 W output power was obtained.

Interaction with DNA and different effect on the nucleus of cancer cells for copper(ii) complexes of N-benzyl di(pyridylmethyl)amine

Three new copper(II) complexes of N-benzyl di(pyridylmethyl)amine (phdpa) were synthesized and characterized by spectroscopic methods. The interaction between CT-DNA and the complexes was studied by UV and fluorescence titration methods. It was found that the complex [(phdpa)Cu(H(2)O)Ac)](Ac), with the non-planar aromatic heterocyclic ring ligand (phdpa), showed good anticancer properties and could cause the fragmentation of the nucleus, although its interaction with CT-DNA was weaker than that of 1,10-phenanthroline (phen)-based copper(II) complexes. The anticancer activities of copper(II) complexes with phdpa and phen based ligands are correlated to their binding constants with DNA, but phen-based copper(II) complexes did not cause the nucleus fragmentation of HeLa cells. [(phdpa)Cu(H(2)O)Ac)](Ac) can noticeably decrease the oxygen content of a culture solution and of HeLa cells, which make it a new nucleus and oxygen related anticancer copper(II) complex. Information obtained here would be helpful in the design of new antitumor complexes in oxidative therapy.

非共面腔激光陀螺复杂象散研究及其光阑设计

Based on 4×4 matrix including meridian and latitude,the round-trip matrix of nonplanar cavity was established.According to the matrix,the q parameters matrix was calculated,the complex astigmatism in some nonplanar cavity ring laser gyro(RLG) was analyzed,and the spot radius of Gaussian beam at any location was obtained theoretically.Then the spot radii of the out-cavity Gaussian beam were measured by CCD,and the Gaussian beam waist was obtained by hyperbola fitting.The result was consistent with the theoretical one.According to spot radii,diaphragm radii and location,the diffraction loss was obtained.The designed diaphragm located at the Gaussian beam waist is circular,and the ratio of diaphragm radius to waist radius is about 2.The designed scheme guarantees the nonplanar cavity RLG works with single TEM00 mode.

Aromaticity of strongly bent benzene rings: persistence of a diatropic ring current and its shielding cone in [5]paracyclophane

Direct evaluation of the induced π current density in [5]paracyclophane (1) shows that, despite the significant non-planarity (α = 23.2°) enforced by the pentamethylene bridge, there is only a modest (ca. 17%) reduction in the π ring current, justifying the use of shielding-cone arguments for the assignment of (1)H NMR chemical shifts of 1 and the claim that the non-planar benzene ring in 1 retains its aromaticity (on the magnetic criterion).

激光二极管抽运的单块非平面环形腔可调谐单频激光器

激光二极管抽运的单块非平面环形腔可调谐单频激光器

Bis(benzo)triazinethionoaza-14-crown-4 ether and its complex with CoBr2: Synthesis and crystal structures

8,11,14-Trioxa-22,24,25-triazatetracyclo[19.3.1.02,7.015,20]pentacosa-2,4,6,15(20),16,18-hexaene-23-thione (L) containing a symmetric triazinethione subunit in its macrocycle and its complex with cobalt(II) bromide of the formula [CoL2Br2] · 0.5CHCl3 (I) were obtained and examined by X-ray diffraction, IR and NMR spectroscopy, and mass spectrometry. It was found that the thiourea fragment in compound L is attached to the nitrogen macrocycle through the C(2) and C(19) atoms, thus forming a substantially nonplanar six-membered triazine ring in a slightly distorted sofa conformation. Its mean-square plane is nearly perpendicular to the mean-square plane of the macrocycle (the dihedral angle between them is 83.3°). Structure L is stabilized by two bifurcate endocyclic hydrogen bonds between the N(1) atom of the triazine ring and the O(1) and O(3) atoms. The size of the macrocyclic cavity is 4.07 A. The coordination polyhedron of the Co atom is a distorted tetrahedron made up of the sulfur atoms of two monodentate terminal molecules L and two bromine atoms.

Performance of planar-waveguide external cavity laser for precision measurements

A 1542-nm planar-waveguide external cavity laser (PW-ECL) is shown to have a sufficiently low level of noise to be suitable for precision measurement applications. Its frequency noise and intensity noise was comparable or better than the non-planar ring oscillator (NPRO) and fiber laser between 0.1 mHz to 100 kHz. Controllability of the PW-ECL was demonstrated by stabilizing its frequency to acetylene ((13)C(2)H(2)) at 10(-13) level of Allan deviation. The PW-ECL also has the advantage of the compactness of a standard butterfly package, low cost, and a simple design consisting of a semiconductor gain media coupled to a planar-waveguide Bragg reflector.

Chelation-Assisted, Copper(II)-Acetate-Accelerated Azide−Alkyne Cycloaddition

We described in a previous communication a variant of the popular Cu(I)-catalyzed azide-alkyne cycloaddition (AAC) process where 5 mol % of Cu(OAc)(2) in the absence of any added reducing agent is sufficient to enable the reaction. 2-Picolylazide (1) and 2-azidomethylquinoline (2) were found to be by far the most reactive carbon azide substrates that convert to 1,2,3-triazoles in as short as a few minutes under the discovered conditions. We hypothesized that the abilities of 1 and 2 to chelate Cu(II) contribute significantly to the observed high reaction rates. The current work examines the effect of auxiliary ligands near the azido group other than pyridyl for Cu(II) on the efficiency of the Cu(OAc)(2)-accelerated AAC reaction. The carbon azides capable of binding to the catalytic copper center at the alkylated azido nitrogen in a chelatable fashion were indeed shown to be superior substrates under the reported conditions. The chelation between carbon azide 11 and Cu(II) was demonstrated in an X-ray single-crystal structure. In a limited set of examples, the ligand tris(benzyltriazolylmethyl)amine (TBTA), developed by Fokin et al. for assisting the original Cu(I)-catalyzed AAC reactions, also dramatically enhances the Cu(OAc)(2)-accelerated AAC reactions involving nonchelating azides. This observation leads to the hypothesis of an additional effect of chelating azides on the efficiencies of Cu(OAc)(2)-accelerated AAC reactions, which is to facilitate the rapid reduction of Cu(II) to highly catalytic Cu(I) species. Mechanistic studies on the AAC reactions with particular emphasis on the role of carbon azide/copper interactions will be conducted based on the observations reported in this work. Finally, the immediate utility of the product 1,2,3-triazole molecules derived from chelating azides as multidentate metal coordination ligands is demonstrated. The resulting triazolyl-containing ligands are expected to bind with transition metal ions via the N(2) nitrogen of the 1,2,3-triazolyl group to form nonplanar coordination rings. The Cu(II) complexes of bidentate T1 and tetradentate T6 and the Zn(II) complex of T6 were characterized by X-ray crystallography. The structure of [Cu(T1)(2)(H(2)O)(2)](ClO(4))(2) reveals the interesting synergistic effect of hydrogen bonding, π-π stacking interactions, and metal coordination in forming a one-dimensional supramolecular construct in the solid state. The tetradentate coordination mode of T6 may be incorporated into designs of new molecule sensors and organometallic catalysts.