Streaking and Wigner time delays in photoemission from atoms and surfaces

Streaked photoemission metrology allows the observation of an apparent relative time delay between the detection of photoelectrons from different initial electronic states. This relative delay is obtained by recording the photoelectron yield as a function of the delay between an ionizing ultrashort extended ultraviolet (XUV) pulse and a streaking infrared (IR) pulse. Theoretically, photoemission delays can be defined based on i) the phase shift the photoelectron wavefunction accumulates during the release and propagation of the photoelectron (``Wigner delay") and, alternatively, ii) the streaking trace in the calculated photoemission spectrum (``streaking delay"). We investigate the relation between Wigner and streaking delays in the photoemission from atomic and solid-surface targets. For solid targets and assuming a vanishing IR-skin depth, both Wigner and streaking delays can be interpreted as an average propagation time needed by photoelectrons to reach the surface, while the two delays differ for non-vanishing skin depths. For atomic targets, the difference between Wigner and streaking delays depends on the range of the ionic potential.Comment: 9 pages, 12 figures, submitted to Phys. Rev.

Psychological Contract Breach and Customer Satisfaction: A Study of Online Shopping

Online shopping is becoming increasingly popular among customers in recent years. It offers customers numerous advantages and benefits, such as convenience in terms of time and place, better prices, and a variety of options. However, the number of customers who complain about online shopping is also increasing. Therefore, it is important for online retailers to better understand how customers respond to failures in customers’ online shopping. Prior research on service failures and customer complaints has largely used expectation-dissatisfaction model to explain the phenomenon (e.g., McCollough, Berry, and Yadav 2000) and suggests approaches to address customer complaints (e.g., Hess, Ganesan, and Klein 2003). The current study takes a psychological contracts perspective and investigates its role in customers’ reactions to service failures. We propose that psychological contracts are held by customers, representing customers’ beliefs about obligations between them and the company. In two experiments, we find that when customers encounter a service failure, they will perceive that there is a breach in the psychological contract, which leads to negative reactions. In addition, the findings from Experiment 1 show that customers’ attribution of breach to intentional rather than misunderstanding will accentuate the relationship between the perceived breach and customers’ negative reactions. Further, we show in Experiment 2 that customers will react less negatively to service failures when they are notified on how the company will handle the service failures than why the failures occurred. The current research will make several theoretical and practical contributions. It examines psychological contract breach as the underlying mechanism for why customers are dissatisfied with online service failures. Two moderators are identified to influence the strength of the relationship to address the inconsistent findings in previous research. Based on above findings, we proposed approaches for companies to communicate more effectively to customers to mitigate customers’ negative reactions to service failures

From Customizing Products to Possessive Bonds: The Role of Consumer Involvement and Consumer Privacy Concern

Despite the prevalence of customized products and service in the marketplace, little research has examined the impact of customization on consumers. The current research investigates the role of brand customization on consumers’ brand relationship and brand attitude. The findings from two experiments demonstrate that consumers with high involvement (vs. low) will have more positive brand relationship and brand attitude. In addition, consumer’s privacy concern moderates this relationship such that the identified positive effect exists only for those with a low privacy concern

Electrical Control of Magnetization in Charge-ordered Multiferroic LuFe2O4

LuFe2O4 exhibits multiferroicity due to charge order on a frustrated triangular lattice. We find that the magnetization of LuFe2O4 in the multiferroic state can be electrically controlled by applying voltage pulses. Depending on with or without magnetic fields, the magnetization can be electrically switched up or down. We have excluded thermal heating effect and attributed this electrical control of magnetization to an intrinsic magnetoelectric coupling in response to the electrical breakdown of charge ordering. Our findings open up a new route toward electrical control of magnetization.Comment: 14 pages, 5 figure

Evaluating Feynman integrals by the hypergeometry

The hypergeometric function method naturally provides the analytic expressions of scalar integrals from concerned Feynman diagrams in some connected regions of independent kinematic variables, also presents the systems of homogeneous linear partial differential equations satisfied by the corresponding scalar integrals. Taking examples of the one-loop $B_{_0}$ and massless $C_{_0}$ functions, as well as the scalar integrals of two-loop vacuum and sunset diagrams, we verify our expressions coinciding with the well-known results of literatures. Based on the multiple hypergeometric functions of independent kinematic variables, the systems of homogeneous linear partial differential equations satisfied by the mentioned scalar integrals are established. Using the calculus of variations, one recognizes the system of linear partial differential equations as stationary conditions of a functional under some given restrictions, which is the cornerstone to perform the continuation of the scalar integrals to whole kinematic domains numerically with the finite element methods. In principle this method can be used to evaluate the scalar integrals of any Feynman diagrams.Comment: 39 pages, including 2 ps figure