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All Journal Jurnal Penelitian Fisika dan Aplikasinya (JPFA) JPSE (Journal of Physical Science and Engineering) Spektra: Jurnal Fisika dan Aplikasinya Jurnal Fisika Indonesia PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL)

Iman Santoso

Departemen Fisika, Fakultas Matematika Dan Ilmu Pengetahuan Alam, Universitas Gadjah Mada Yogyakarta Sekip Utara BLS 21 Yogyakarta 55821

Author-ID : 483094

Aerospace Engineering Astronomy Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Physics Other

Published : 7 Documents Claim Missing Document

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Articles

Optical Properties Comparison of Carbon Nanodots Synthesized from Kangkung (Ipomoea aquatica) with Deep Frying and Roasting Techniques Wipsar Sunu Brams Dwandaru; Fika Fauzi; Dyah Silviana Sari; Emi Kurnia Sari; Iman Santoso; Haris Suhendar
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol. 9 No. 2 (2019)
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v9n2.p123-131

Carbon nanodots (Cdots) have many unique properties such as luminescence that can be utilized in various fields. The purposes of this study are to synthesize Cdots from kangkung (Ipomoea aquatica) through frying and roasting techniques and compare the optical properties of the Cdots using UV-Vis, PL, and FTIR. Three stages of synthesizing process of Cdots, i.e.: preparing the kangkung powder (root, stem, leaf) and synthesizing the Cdots through frying and roasting techniques. Each part (root, stem, and leaf) was heated in an oven at 250 oC for 2 hours and mashed into powder. The frying method was done by frying 15 g of the powder in 120 ml oil for 5 minutes at 88 oC, filtered, and dissolved in n-hexane. In addition, the roasting method was done by frying the powder without oil as much as 15 g for 5 minutes, dissolved in 120 ml of distilled water, and then filtered. The UV-Vis characterization showed one absorbance peak for Cdots via frying and roasting techniques at 293 nm to 296 nm and 262 nm to 282 nm, respectively. The Cdots through frying and roasting techniques produce red and green luminescence, respectively. The FTIR characterization showed the presence of C=C and C=O functional groups, which are the core and surface state of the Cdots by frying technique, while the samples via roasting technique showed only the core. It can be concluded that the Cdots samples obtained from frying and roasting methods have different optical properties. The frying method produces Cdots with longer wavelength at the absorbance peak in the UV-Vis test compared to the roasting method. Moreover, the frying and roasting methods produce different color luminescence.

Reduced Graphene Oxide/Polyvinyl Alcohol Nanofibers Fabricated by Electrospinning Technique as An Ideal Candidate for Organic Solar Cell Devices Asriani Asriani; Iman Santoso
JPSE (Journal of Physical Science and Engineering) Vol 6, No 1 (2021): JPSE (Journal of Physical Science and Engineering)
Publisher : Universitas Negeri Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar

Functionalization of rGO that previously obtained by chemical reduction using hydrazine hydrate, has been done by changing its morphology into nanofiber with electrospinning technique and using PVA as a polymer matrix. The rGO nanofibers that had been formed were then characterized using Fourier Transformation-Infra Red (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and UV-Vis Spectrophotometer. FTIR spectroscopy confirmed the presence of C – C group and C = O group in nanofibers. SEM showed the change of nanofibers morphology which is marked by the increasing of fibres diameter and the hollow fibres become brighter. Furthermore, the effect of rGO concentration to nanofiber optical properties was confirmed by UV-Vis spectrophotometer. According to this characterization, the absorbance of rGO/PVA nanofiber is decreased due to increased rGO concentration. The detail of optical properties of rGO is studied through complex refractive index and dielectric constant in which Kramers-Kronig transformation is then employed to calculate complex refractive index and complex dielectric constant. From the data, the optical properties of rGO/PVA nanofibers indicating that rGO/PVA nanofibers can be applied as transparent electrode an organic solar cell devices.DOI: 10.17977/um024v6i12021p010

UV-VISIBLE OPTICAL ABSORBANCE OF GRAPHENE OXIDE IN COPPER IONIC LIQUID SYNTHESIZED VIA ELECTROCHEMICAL METHOD ASSISTED BY A COPPER COIL Wipsar Sunu Brams Dwandaru; Oktiana Lusi Priyani; Bagas Prakoso; Rhyko Irawan Wisnuwijaya; Iman Santoso; Arif Rahman
Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

An optical absorbance study using Ultraviolet-Visible (UV-Vis) spectrophotometer device has been conducted on graphene oxide (GO) in copper (Cu) ionic liquid using electrochemical exfoliation combined with a direct current (DC) electrical circuit of copper coil given inside the electrolyte solution. The electrolyte solutions used are sulfuric acid (H2SO4) and chloride acid (HCl). The UV-Vis spectrum of the samples shows absorbance peaks at around 214 nm to 218 nm and shouldering peaks around 245 nm to 249 nm. The first peak corresponds to the existence of copper (Cu) ionic liquid in the solution, whereas the shouldering peak is related to the occurrence of GO material. A comparison between UV-Vis spectral of graphite in dimethylformamide (DMF) and GO in Cu ionic liquid in DMF resulted in the existence of a blue shift which signifies the production of Cu ionic liquid from the Cu coils inside the electrolyte solution. Increasing the concentration of the solution increases the absorbance peaks. Furthermore, raising the number of loops yields in the increase of the absorbance value at the first peaks that show Cu ionic liquid, but tends to decrease the absorbance value of the shouldering peaks of the GO material.

Perhitungan Konstanta Dielektrik Lapisan Tipis Graphene Monolayer Si-Face Hasil Pengukuran Synchrotron dengan Metode Kramers-Kronig dan Newton-Raphson (Halaman 49 s.d. 53) Lisa’ Yihaa Roodhiyah; Andrivo Rusydi; Iman Santoso
Jurnal Fisika Indonesia Vol 19, No 56 (2015)
Publisher : Department of Physics Universitas Gadjah Mada

Telah dilakukan perhitungan konstanta dielektrik nanostruktur epitaxial graphene monolayer pada substrat Si-face SiC dari hasil pengukuran data reflektivitas dengan metode Kramers-Kronig dan Newton-Raphson. Data yang digunakan yaitu data reflektivitas pada rentang energi 0.5 – 30 eV dari pengukuran di Hasylab Synchroton. Metode Kramers-Kronigmenghasilkan beda fase δ dan dengan menggunakan persamaan Fresnel dan persamaan Snelliusdigunakan untuk mengekstraksi konstanta dielektrik. Permasalahan pencarian titik nol dalam persamaan Fresnel ketika mengekstraksi konstanta dielektrik dapat diselesaikan dengan metode numerik Newton-Raphson. Hasil yang diperoleh menunjukkan beberapa hal penting : 1) metode Kramers-Kronig dan numerik Newton-Raphson dapat digunakan untuk mengekstraksi konstanta dielektrik graphene monolayer Si-face, 2) adanya puncak absorbsi asimetri pada energi 4,6, 6,1 dan 8,4 eV ditinjau dari bagian imajiner konstanta dielektrik dan indeks bias, 3) puncak pada energi 6,1 dan 8,4 eV berasal dari resonansi exitonic akibat adanya interaksi elektron-elektron dan elektron-hole dan puncak pada energi 4,6 eV berasal transisi antar pita (interband) dari π band ke π* band yang dimiliki material graphene monolayer.

Kajian Struktur Pita Elektronik Graphene dan Graphane Menggunakan Model Ikatan Kuat Realistik dengan Ketakteraturan (halaman 28 s.d. 33) Muhammad Qosim; Iman Santoso
Jurnal Fisika Indonesia Vol 19, No 55 (2015)
Publisher : Department of Physics Universitas Gadjah Mada

Dua model matriks hasil modifikasi model ikatan kuat untuk mendekati struktur pita elektronik graphene dan graphane dengan banyak atom beserta beberapa macam ketakteraturannya telah berhasil disusun. Model total menjumlahkan matriks tansfer dan overlap tiap unit cell berukuran 2 × 2 elemen untuk graphene dan 4 × 4 elemen untuk graphane. Model diagonal menyusun tiap unit cell secara diagonal pada matriks transfer dan overlapnya dengan ukuran 2N × 2N elemen untuk graphene dan 4N × 4N elemen untuk graphane (N = jumlah unit cell).Model-model matriks tersebut kemudian didiagonalisasi secara numerik untuk dihasilkan grafik dispersi energi dan rapat keadaan. Pengkajian lebih lanjut tentang ketakteraturan diawali dengan simetrisasi rapat keadaan yaitu membuang matriks overlap s dan mereduksi nilai parameter hopping menjadi 1 eV. Variasi parameter hopping next nearest neighbour t’ hanya mengubah rentang pita energi dan menggeser titik K paralel dengan sumbu momentum.

Perhitungan Numerik Rapat Keadaan Graphene Monolayer Menggunakan Metode Newton Raphson (Halaman 53 s.d. 56) Ilham Pebrika; Iman Santoso
Jurnal Fisika Indonesia Vol 19, No 55 (2015)
Publisher : Department of Physics Universitas Gadjah Mada

Telah dilakukan perhitungan secara numerik terhadap rapat keadaan pada graphene layer tunggal. Rapat keadaan dihitung berdasarkan persamaan energi dispersi E(k) pada energi rendah. Pada umumnya rapat keadaan dihitung secara numerik menggunakan persamaan N(E) = Nf ∑k δ(E − E(k)), yakni ketika posisi ε = E(k) dengan Nf merupakan faktor degenerasi. Nilai N(E) dikelompokan berdasarkan nilai-nilai yang hampir sama yang kemudian dijumlahkan menjadi nilai rapat keadaan. Hanya saja metode ini memiliki ralat yang lebih besar karena nilai N(ε) yang diperoleh dianggap sama dengan nilai yang terdekat. Pada kajian ini nilai rapat keadaan dihitung dengan metode yang berbeda yakni mengimplementasikan nilai ε = E(k) tetapi dengan pendekatan nilai yang mendekati nilai yang sebenarnya. Nilai tersebut direpresentasikan dengan nilai akar-akar dari persamaan energi dispersi dikurangi nilai level energi E sebegai fungsi pembuat nol (E(k) − E). Nilainya dapat dihitung dengan metode newton-raphson. Nilai akar ini kemudian diidentiﬁkasikan dengan nilai 1 dan dijumlahkan per level energi E sehingga setiap levelnya memiliki nilai rapat keadaan yang telah dijumlahkan berdasarkan banyak akar yang ada. Dari perhitungan rapat keadaan menggunakan metode newton-raphson diperoleh nilai yang sama dengan perhitungan yang telah dilakukan sebelumnya.

SINTESIS GRAPHENE OXIDE DAN REDUCED GRAPHENE OXIDE Yeti Rafitasari; Haris Suhendar; Nurul Imani; Fitri Luciana; Hesti Radean; Iman Santoso
PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) Vol 5 (2016): PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) SNF2016
Publisher : Program Studi Pendidikan Fisika dan Program Studi Fisika Universitas Negeri Jakarta, LPPM Universitas Negeri Jakarta, HFI Jakarta, HFI

Graphene oxide (GO) and reduced graphene oxide (rGO) have been synthesized chemically from graphite powder. Graphite powder was oxidized with strong oxidator agent molekul to get graphite oxide, this process was called by Hummerâ€™s methode. Graphite oxide was dispersed in water with ultasonic vibrator to exfoliated graphite oxide layers, and become graphene oxide. Epoxy group in GO structure was reduced by hydrazine 80 wt% to get rGO. Comparation was done between self synthetic rGO and Sigma Aldrich synthetic rGO using UV-Vis and FTIR spectroscopy, which showed that optical properties of self synthetic rGO have same UV-Vis and FTIR spectroscopy with Sigma Aldrich synthetic rGO. Keywords: Graphene Oxide, Reduced Graphene Oxide, Sigma Aldrich, Optical Properties.

Co-Authors Andrivo Rusydi Arif Rahman Asriani Asriani Bagas Prakoso Dyah Silviana Sari Emi Kurnia Sari Fika Fauzi Fitri Luciana Haris Suhendar Hesti Radean Ilham Pebrika Lisa’ Yihaa Roodhiyah Muhammad Qosim Nurul Imani Oktiana Lusi Priyani Rhyko Irawan Wisnuwijaya Wipsar Sunu Brams Dwandaru Yeti Rafitasari

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