Possible shape-change observed at high spin in123Cs

The collective moment of inertia ? _band ⁽²⁾ of¹²³Cs produced in the¹¹⁵In+¹²C reaction at 80 MeV has been measured by gamma-gamma energy correlation techniques. The variations of ? _band ⁽²⁾ with the rotational frequency are compared to those of¹²²Xe and analysed in the frame of a cranked Nilsson-Strutinsky model. We conclude that the addition of one proton to the triaxial (γ?30°)¹²²Xe core gives a final prolate-type nucleus¹²³Cs withγ?0° above a rotational frequency?ω?0.55 MeV.     

Pentagrams and Paradoxes

Klyachko and coworkers consider an orthogonality graph in the form of a pentagram, and in this way derive a Kochen-Specker inequality for spin 1 systems. In some low-dimensional situations Hilbert spaces are naturally organised, by a magical choice of basis, into SO(N) orbits. Combining these ideas some very elegant results emerge. We give a careful discussion of the pentagram operator, and then show how the pentagram underlies a number of other quantum “paradoxes”, such as that of Hardy.     

Asymmetric Synthesis of 2,4,5‐Trisubstituted Δ2‐Thiazolines

Δ²‐Thiazolines are interesting heterocycles that display a wide variety of biological characteristics. They are also common in chiral ligands used for asymmetric syntheses and as synthetic intermediates. Herein, we present asymmetric routes to 2,4,5‐trisubstituted Δ²‐thiazolines. These Δ²‐thiazolines were synthesized from readily accessible/commercially available α,β‐unsaturated methyl esters through a Sharpless asymmetric dihydroxylation and an O→N acyl migration reaction as key steps. The final products were obtained in good yields with up to 97 % enantiomeric excess.     

Carbon atom fluorescence and C2 emission detected in fuel-rich flames using a UV laser

Laser-induced fluorescence from carbon atoms, excited at the two-photon resonances around 280 nm, has been detected in fuel-rich hydrocarbon flames together with Swan band emission from the C₂ radical, which was non-resonantly excited at the same wavelengths. The emission from the C atom and from the C₂ molecule exhibited several similarities, indicating a possible common photo-chemical origin.     

131La形状共存和带终止

用组态相关推转Nilsson-Strutinsky模型研究了¹³¹La转动带结构性质.对一些特殊组态带的形状共存和带终止做了较为详细的探讨,并把理论计算结果与实验结果进行了比较.理论计算结果表明,¹³¹La是软γ形变核,很多具有不同组态的转动带都有形状共存.实验上测量的¹³¹La的宇称和辛量子数为(π,α)=(+,±1/2)的转动带的组态是[02,8],即组态π(h_11/2)²⊙ν(h_11/2)⁸,其中负辛量子数带几乎达到该带的带终止理论预言值I=41.5h,但是该带对实验上测量带终止不利,因为接近带终止态时能量增加太快.     

Lifetimes of triaxial superdeformed states in 163Lu and 164Lu

Lifetimes of states in the yrast superdeformed bands of ¹⁶³Lu and ¹⁶⁴Lu were determined in a Doppler-shift attenuation-method experiment. From fractional Doppler shifts and line shapes, average transition quadrupole moments, Q _t = 8.2_-0.6 ^+1.0 b and 7.1_-0.6 ^+0.5 b, were deduced for one of the bands in ¹⁶³Lu and ¹⁶⁴Lu, respectively. These values are much larger than the quadrupole moment of the normal-deformed yrast band in ¹⁶³Yb, Q _t = 4.9_-0.4 ^+1.3 b, that was also determined in this experiment. Comparison to cranking calculations indicates that both superdeformed bands correspond to a local potential energy minimum with a pronounced triaxiality, γ∼ 20^°. Received: 8 November 2001 / Accepted: 9 January 2002     

Is rotational CARS an alternative to vibrational CARS for thermometry?

Recent developments in rotational CARS thermometry and critical issues when comparing vibrational and rotational CARS thermometry are described. In particular, the development of dual broadband rotational CARS and the noise characteristics of this approach are emphasized. The difficulty with unambiguous temperature determination in vibrational CARS with unknown parameters, in particular the nonresonant background susceptibility, and the lower sensitivity of rotational CARS thermometry at flame temperatures are also discussed.