ABSTRAKTelah dilaksanakan penelitian ZnO dan ZnO doping tembaga yang bertujuan untuk mengetahui sifat optik material tersebut meliputi nilai absorbansi dan celah pita energi. Penelitian ini diselesaikan dengan menggunakan metode liquid phase deposition atau kimia basah yang dilakukan dengan konsentrasi tembaga 0 dan 11%, selanjutnya dilakukan pemanasan pada microwave kemudian dikarakterisasi nilai absorbansi dan energi gap dengan spektrofotometri UV-VIS. Hasil yang diperoleh pada penelitian ini adalah ZnO:Cu 0% dan 11% memiliki serapan paling tinggi berada disekitar panjang gelombang 344 nm dan 358 nm, Setelah menentukan nilai absorbansinya kemudian menganalisis nilai celah pita energi dengan konsentrasi 0% dan 11% diperoleh nilai celah pita energi secara berurutan yaitu 3.37 eV dan 3.31 eV. Penambahan doping Tembaga mengakibatkan puncak absorbansi bergeser kearah panjang gelombang yang lebih besar. Sehingga dapat dikatakan bahwa bahwa ZnO:Cu baik 0% maupun 11% merupakan karakterisaasi bahan yang dapat mengabsorbsi cahaya UV. Kata kunci: semikonduktor; sifat optik; absorbansi; celah pita energi. ABSTRACTResearch has been carried out on copper doped ZnO and ZnO which aims to determine the optical properties of these materials including absorbance values and energy band gaps. This research was completed using the liquid phase deposition method or wet chemistry which was carried out with copper concentrations of 0 and 11%, then heating in the microwave and then characterizing the absorbance value and energy gap by spectrophotometry UV-VIS. The results obtained in this study are ZnO:Cu 0% and 11% have the highest absorption around the wavelengths of 344 and 358 nm. After determining the absorbance value, then analyzing the energy band gap value with a concentration of 0% and 11%, the energy band gap values obtained respectively are 3.37 eV and 3.31 Ev. The addition of copper doping causes the absorbance peak to shift towards a larger wavelength, So it can be said that ZnO:Cu both 0% and 11% is a characterization of materials that can absorb UV light. Keywords: semiconductors; optical properties; absorbance; energy gap.

A major function of soil is to provide fundamental natural resources for the survival of plants, animals, and the human race. The maintenance of soil quality is critical for ensuring the sustainability of the environment and it depends on the balances of soil structure and nutrient composition. To determine soil quality, several methods were already widely used in which most of them were based on solvent extraction followed by other laboratory procedures. However, these methods often require laborious and complicated processing for samples. Infrared reflectance spectroscopy can be considered as a rapid, innovative and nondestructive method for determining soil properties. The objective of this study is to apply infrared technology in classifying soils based on their land-use and to predict related soil quality properties based on its infrared reflectance. Soil infrared spectrum was acquired in the wavelength range from 1000 to 2500 nm for ricefield (with a total of 30 points) and ground-field soils (31 points). Principal component analysis (PCA) with non-iterative partial least square (NIPALS) was applied to analyze soils spectral data. The result showed that two principal components (PC1=97% ad PC2 = 3%) based on infrared reflectance data were successfully able to recognize and distinguish soils based on their landuse. Furthermore, the wavelength ranges of 950-1128 were related to soil nitrogen content whilst 1460 nm and 1920 nm were associated with soil moisture content. Soil organic matter can be predicted in the wavelength range of 1230-1315 nm, 1580-1680 nm, and 2095-2200 nm. This may conclude that infrared technology was feasible to use as a rapid, innovative and non-destructive method in soils quality properties classification and evaluation.