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Magnetic properties
Ferromagnetism Paramagnetism. Ferrimagnetism Antiferromagnetism
Ordered and same magnitude without external magnetic field
Disordered without external magnetic fieldIn the external mag-netic field, the mo-ments are ordered.
Aligned oppositely with different magni-tude
Aligned oppositely with the same magni-tudes
Superparamagnetism
• Superparamagnetism is a form of magnetism, which appears in small ferromagnetic or ferromagnetic nanoparticle.
• Neel relxation time < measurement time→average zero magnetic state = superparamagnetic state
• When an external magnetic field is applied to an assembly of superparamagnetic nanoparticles, their magnetic moments tend to align along the applied field, leading to a net magnetization.
N S
Nanoparticle
Optical properties
IGOR L. MEDINTZ1*, H. TETSUO UYEDA2, ELLEN R. GOLDMAN1 AND HEDI MATTOUSSI, Quantum dot bioconjugates for imaging, labelling and sensing, Nature materials 2005
Alexa 488
FITC
GFP Quantum dots
Organic dye
0 10 20 30 40 50 60 70 80 90100
110120
130140
1500
0.2
0.4
0.6
0.8
1
1.2
Photobleaching time
FITC Alexa Flour 488GFP QD 608
Time(sec)
Rela
tive
inte
nsity
Qd is Much Much stable!
3. Nanoruler
• Alexander J. Mastroianni, David A. Sivak, Phillip L. Geissler, and A. Paul Alivisatos, Probing the Conformational Distributions of Subpersistence Length DNA, Biophysical Journal 2009
.
3. Nanoruler
• Alexander J. Mastroianni, David A. Sivak, Phillip L. Geissler, and A. Paul Alivisatos, Probing the Conformational Distributions of Subpersistence Length DNA, Biophysical Journal 2009
.
Dark Field – Gold nanoparticles TIRF Microscopy – Quantum dots
Q dot
Magnetic+Au
Completely matching!
Glass
Strong magnet
TIRF Microscopy
Strong magnet
References• A.P.Alivisatos, Science, New Series, Vol. 271, No. 5251. (Feb. 16, 1996), pp. 933-937• Yadong Yin & A.Paul Alivisatos, NATURE04165, vol 437, 2005• J. M. Yuk, J.W. Park, A. Paul Alivisatos, High-resolution EM of Colloidal Nanocrystal growth using graphene liquid cells, Science 336, 61 (2012) • J. M. Yuk, J.W. Park, A. Paul Alivisatos, High-resolution EM of Colloidal Nanocrystal growth using graphene liquid cells, Science 336, 61 (2012) • Xiaogang Peng, L.Manna, W.Yang, J. Wickham, E.Scher, A.Kadavanich & A.P.Alivisatos, Shape control of CdSe nanocrystals, Nature,vol 404, 2 March 2000• L.Manna, D.J.Milliron, A.Meisel, E.C.Scher, A.Paul Alivisatos, Controlled growth of tetrapod-branched inorganic nanocrystals, nature materials, vol 2,June 2003• Haitao Liu and A.Paul Alivisatos, Preparation of Asymmetric Nanostructures through Site Modification of Tetrapods,Nano Lett., Vol. 4, No. 12, 2004 • Son, D. H.; Hughes, S. M.; Yin, Y. D.; Alivisatos, A. P., Cation exchange reactions-in ionic nanocrystals. Science 2004, 306, (5698), 1009-1012• Robinson, R. D.; Sadtler, B.; Demchenko, D. O.; Erdonmez, C. K.; Wang, L. W.; Alivisatos, A. P., Spontaneous superlattice formation in nanorods through partial cation exchange. Science 2007, 317, (5836), 355-358• IGOR L. MEDINTZ1*, H. TETSUO UYEDA2, ELLEN R. GOLDMAN1 AND HEDI MATTOUSSI, Quantum dot bioconjugates for imaging, • labelling and sensing, Nature materials 2005• Alexander J. Mastroianni, David A. Sivak, Phillip L. Geissler, and A. Paul Alivisatos, Probing the Conformational Distributions of Subpersistence Length DNA, Biophysical Journal 2009