1. MKI80004 - Instrumentasi Kimia
Minggu Ke
Isi Pertemuan
Keterangan 1
Uraian Perkuliahan: Isi Kuliah; Cara; dan Evaluasi
Pendahuluan/Introducton to Spectrometry
Lecturing & Discussion 2
Optical Spectroscopy and Instrumentation; UV-Vis [Absorption, Reflectance aspect] Spectrometry; Luminescence Spectroscopy 3
Infra Red [Absorption Spectrometry, Reflectance aspect ] Spectrometry 4
Introduction to Atomic Spectrometry
Atomic Emission Spectroscopy
Atomic Absorption Spectroscopy 5
Atomic Spectrometry with X Ray:
XRF
XPS 6 7
Class Discussion and Evaluation 8
Overview Other Instrumental Methods: Hyphenated Techniques 9
Topic of Choice I [1& 2]
Active Learning 10
Topic of Choice II [1& 2] 11
Topic of Choice III [1& 2] 12
Topic of Choice IV [1& 2] 13
Evaluation
Short Talk 14
Final Evaluation

46. Cuvet

66. Violet:   nm
Indigo:   nm
Blue:   nm
Green:   nm
Yellow:   nm
Orange:   nm
Red:   nm

71. Methyl bromide Methyl Iodide
Chromophore
Example
Excitation
λmax, nm ε
Solvent
C=C
Ethene
π  __>   π*
171
15,000
hexane
C≡C
1-Hexyne
180
10,000
C=O
Ethanal
n  __>  π* π  __>  π*
15 10,000
hexane hexane
N=O
Nitromethane
17 5,000
ethanol ethanol
C-X   X=Br       X=I
Methyl bromide Methyl Iodide
n  __>  σ* n  __>  σ*

72. Nature of Shift Descriptive Term
To Longer Wavelength
Bathochromic
To Shorter Wavelength
Hypsochromic
To Greater Absorbance
Hyperchromic
To Lower Absorbance
Hypochromic
Terminology for Asorption Shifts

76. Empirical Rules for Absorption Wavelengths of Conjugated Systems
Core Chromophore
Substituent and Influence
                                           Transoid Diene 215 nm
R- (Alkyl Group)   ....   +5 nm RO- (Alkoxy Group)   ..   +6 X- (Cl- or Br-)     +10 RCO2- (Acyl Group)   ....   0 RS- (Sulfide Group)   ..   +30 R2N- (Amino Group)   ..   +60
Further π -Conjugation
C=C (Double Bond)   ...   +30 C6H5 (Phenyl Group) ...   +60
                                 Cyclohexadiene* 260 nm
                      (i) Each exocyclic double bond adds 5 nm. In the example on the right, there are two exo-double bond components: one to ring A and the other to ring B. (ii) Solvent effects are minor. * When a homoannular (same ring) cyclohexadiene chromophore is present, a base value of 260 nm should be choosen. This includes the ring substituents. Rings of other size have a lesser influence.
Empirical Rules for Absorption Wavelengths of Conjugated Systems
Woodward-Fieser Rules for Calculating the λmax of Conjugated Dienes and Polyenes
λmax (calculated) = Base (215 or 260) + Substituent Contributions

77. Some examples that illustrate these rules follow.

78. Woodward-Fieser Rules for Calculating the π __> π
Woodward-Fieser Rules for Calculating the π __>  π* λmax of Conjugated Carbonyl Compounds
Core Chromophore
Substituent and Influence
                                        R = Alkyl   215 nm R = H   210 nm R = OR'   195 nm
α- Substituent   R- (Alkyl Group)   +10 nm   Cl- (Chloro Group)   +15   Br- (Chloro Group)   +25   HO- (Hydroxyl Group)   +35   RO- (Alkoxyl Group)   +35   RCO2- (Acyl Group)   +6 β- Substituent   R- (Alkyl Group)   +12 nm   Cl- (Chloro Group)   +12   Br- (Chloro Group)   +30   HO- (Hydroxyl Group)   +30   RO- (Alkoxyl Group)   +30   RCO2- (Acyl Group)   +6   RS- (Sulfide Group)   +85   R2N- (Amino Group)   +95 γ & δ- Substituents   R- (Alkyl Group)   +18 nm (both γ & δ)   HO- (Hydroxyl Group)   +50 nm (γ)   RO- (Alkoxyl Group)   +30 nm (γ)
Further π -Conjugation
 C=C (Double Bond)   ...   +30  C6H5 (Phenyl Group) ...   +60
                                  Cyclopentenone 202 nm
                                                     
                      (i) Each exocyclic double bond adds 5 nm. In the example on the right, there are two exo-double bond components: one to ring A and the other to ring B. (ii) Homoannular cyclohexadiene component adds +35 nm (ring atoms must be counted separately as substituents) (iii) Solvent Correction: water = –8; methanol/ethanol = 0; ether = +7; hexane/cyclohexane = +11
λmax (calculated) = Base + Substituent Contributions and Corrections

79.                                                                                                                                                                                                              
Figure 1: Schematic diagram of UV-vis diffuse reflectance measurement system.

80. Figure 2: UV-vis diffuse reflectance spectrum for bulk Bi2O3. F(R) =
 = 
(1-R)2  2R
The Kubelka-Munk function, F(R), allows the optical absorbance of a sample to be approximated from its reflectance:
For a semiconductor sample this allows the construction of a Tauc Plot - (F(R).hv)n vs hv. For a direct band gap semiconductor the plot n = 1/2 will show a linear Tauc Region just above the optical absorption edge. Extrapolation of this line to the photon energy axis yields the semiconductor band gap- a key indicator of its light harvesting efficiency under solar illumination. Indirect band gap materials show a Tauc Region on the n = 2 plot.

81.                                                                                                                            
Figure 3: Tauc Plot (n = 1/2) for bulk Bi2O3 after Finlayson et al. Phys. Stat. Sol.

82. Katalis
Hasil Pengukuran Reflectant
Acessories IR
XRF dan XPS