Browsing by Subject "Relaxation time"

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    Non-thermal material and tissue processing with 100 MHz and 500 MHz repetition rate bursts
    (IEEE, 2013) Kerse, Can; Kalaycıoğlu, Hamit; Akaalan O.; Eldeniz, Y.B.; İlday, F. Ömer; Hoogland H.; Holzwarth, R.
    There are a number of applications that would avail a pulse pattern in the form of closely grouped and uniformly spaced pulses, i.e., bursts [1]. Closely grouped pulses with pulse to pulse separation in the order of a few nanoseconds have a potential for increasing material removal rates [2] and thereby reducing the thermal effects. Besides, keeping the burst repetition period in the order of thermal relaxation time has the advantage of keeping the overall average power at lower levels in order to prevent the cumulative heating of the material. © 2013 IEEE.
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    Reduced density matrix approach to phononic dissipation in friction
    (2000) Özpineci, A.; Leitner, D. M.; Çıracı, Salim
    Understanding mechanisms for energy dissipation from nanoparticles in contact with large samples is a central problem in describing friction microscopically. Calculation of the reduced density matrix appears to be the most suitable method to study such systems that are coupled to a large environment. In this paper, the time evolution of the reduced density matrix has been evaluated for an arbitrary system coupled to a heat reservoir. The formalism is then applied to study the vibrational relaxation following the stick-slip motion of an asperity on a surface. The frequency and temperature dependence of the relaxation time is also determined. Predictions of the reduced density matrix are compared with those obtained by using the Golden Rule approach.