From Nanoparticles to Particulate Films
18.6.12, 12:00
Room 308/8
We investigated the spectral response of electromagnetic (EM) energy absorption in a colloidal system of Fe_3 O_4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of sodium dodecyl sulfate (SDS). The temperature of the nanoparticles and the SDS solution was evaluated by a new method based on measuring the Q-factor of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles--SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM field energy was accompanied by a small temperature rise of the system. Measurements of the electron spin resonance (ESR) spectrum of the Fe_3 O_4 nanoparticles presented a slightly asymmetric singlet with g = 2 and a line-width of ∆H = 0.1 mT. It is shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles
Room 308/8
We investigated the spectral response of electromagnetic (EM) energy absorption in a colloidal system of Fe_3 O_4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of sodium dodecyl sulfate (SDS). The temperature of the nanoparticles and the SDS solution was evaluated by a new method based on measuring the Q-factor of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles--SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM field energy was accompanied by a small temperature rise of the system. Measurements of the electron spin resonance (ESR) spectrum of the Fe_3 O_4 nanoparticles presented a slightly asymmetric singlet with g = 2 and a line-width of ∆H = 0.1 mT. It is shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles
