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Abstrak :
Human teeth enamel have been irradiated with gamma radiation from Co60 at room temperature and at liquid nitrogen temperature. Paramagnetic centers are formed and have been detected by using electron spin resonance (ESR) spectrometer at room temperature. The main signal is very stable asymmetric singlet, and attributed to h centers in the hydroxyapatite crystals. It is revealed that several factors influence the amplitude of the asymmetric signal. The amplitude and pattern of the asymmetric signal which depend on the orientation of the sample with respect to the magnetic field are analyzed. Based on the properties of the asymmetric signal the difference between the microcrystal arrangement of healthy and diseased teeth are explained.

Abstrak :
Radiasi merupakan salah satu faktor pembentuk radikal bebas, itu sebabnya petugas yang bekerja di bagian radiasi rentan untuk terpapar radiasi sehingga menimbulkan radikal bebas. Eksperimen ini bertujuan untuk mengetahui seberepa besar pengaruh radiasi terhadap pembentukan radikal bebas pada sampel kuku dan mempelajari proses peluruhan radikal bebas tersebut. Untuk memudahkan eksperimen ini, sampel kuku diradiasi dengan dosis kecil 0,5 Gy, 1 Gy, 3 Gy, 5 Gy dan 10 Gy. Selain itu, untuk mempelajari peluruhan radikal bebas sampel kuku diradiasi dengan dosis besar yaitu 100, 200, dan 300 Gy, kemudian mengukur ulang dengan ESRsetelah satu jam. Yang terakhir adalah pengukuran kuku pada petugas radiasi di sumber gamma cell. Hasil Electron Spin Resonance (ESR) menunjukan bahwa sampel kuku mengandung jumlah radikal bebas yang sesuai dengan banyaknya dosis yang diberikan dan mengalami penurunan jumlah radikal bebas setelah satu jam.

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Radiation is one factor that forming free radicals, thats why radiation employee has a risk to get irradiated by radiation source nearby . This experiment meant to know how much radiation effect to free radical forming and learn process of freeradical decay. To ease this experiment, fingernail samples were irradiated bygamma with variated dose 0,5, 1, 3, 5 and 10 Gy. Beside that, to learn free radicaldecay, fingernails were irradiated with variated dose 100, 200, and 300 Gy, thenfingernails measured by ESR after one hour. The last is ESR measurement forfingernails of radiation employee. Electron Spin Resonance (ESR) result showedthat fingernails contain number of free radicals as much as radiation dose andbeing decreased after one hour irradiated.

Abstrak :
Defek dangling bond dari lapisan tipis amorf silikon karbon (a-SiC:H) hasil deposisi metode dc sputtering telah dipelajari dengan spektroskopi ESR (electron spin resonance). Densitas spin berkurang tidak terlalu besar dengan peningkatan fl ow rate gas metan. Pengaruh kehadiran karbon dan hidrogen terhadap harga-g menunjukkan bahwa sampai fl ow rate gas metan 8 sccm, sinyal ESR didominasi oleh karakteristik defek a-Si:H, sedangkan untuk fl ow rate gas metan lebih besar dari 8 sccm, harga-g berkurang mendekati harga-g dari a-C:H. Hasil analisis inframerah menunjukkan semakin banyak karbon dan hidrogen yang membentuk ikatan Si-H, Si-C dan C-H dengan bertambahnya fl ow rate gas metan. Relasi hasil yang diperoleh dari inframerah dengan densitas defek dan harga-g akan dipelajari.

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The dangling bond defect density in sputtered amorphous silicon carbon alloys have been studied by electron spin resonance (ESR). The results show that the spin density decreased slightly with increasing methane fl ow rate (CH4). The infl uence of carbon and hydrogen incorporation on g-value revealed that for CH4 fl ow rate up to 8 sccm, the ESR signal is dominated by defects characteristic of a-Si:H fi lms and for CH4 fl ow rate higher than 8 sccm the g-value decreased towards those usually found in a-C:H fi lms. Infrared (IR) results suggest that as CH4 fl ow rate increases more carbon and hydrogen is incorporated into the fi lms to form Si-H, Si-C and C-H bonds. A direct relation between the IR results and the defect density and g-value is observed.

Abstrak :
The magnetic susceptibility and high magnetic ESR measurement of SrCu2(PO4)2 has been performed at temperatures ranging from 4.2 K to 300 K and 4.2 K to 77 K, respectively. The magnetic susceptibility shows a broad maximum around T = 40 K. The magnetic susceptibility has been interpreted in terms of one-dimensional magnetic systems. The temperature dependence of the magnetic susceptibility indicated a good agreement with 4-spin alternating configuration model. In the ESR measurement, clear electron spin resonance (ESR) was observed. The integrated intensity for 120 and 301 GHz has a broad maximum at around 40 K, which is consistent with the susceptibility result. A quantitative description gives resonance is the first and second triplet excited states of the excitation spectrum of 4-spin alternating chain configuration. The g1, g2 and g3 values are approximately 2.21 at temperature above 40 K. The g2 dan g3 values have the dependence of temperature under 40 K.