You will be provided with a reference and some statements. Please determine whether each statement is 'supported', 'unsupported', or 'unknown' with respect to the reference. Please note:
First, assess whether the reference contains any valid content. If the reference contains no valid information, such as a 'page not found' message, then all statements should be considered 'unknown'.
If the reference is valid, for a given statement: if the facts or data it contains can be found entirely or partially within the reference, it is considered 'supported' (data accepts rounding); if all facts and data in the statement cannot be found in the reference, it is considered 'unsupported'.

You should return the result in a JSON list format, where each item in the list contains the statement's index and the judgment result, for example:
[
    {
        "idx": 1,
        "result": "supported"
    },
    {
        "idx": 2,
        "result": "unsupported"
    }
]

Below are the reference and statements:
<reference>
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</reference>

<statements>
1. The constituent elements of LiNbO3 possess distinctly different atomic weights and surface binding energies, so physical ion bombardment selectively sputters lighter oxygen and lithium atoms at higher rates than the heavier niobium atoms
2. The preferential sputtering of lighter oxygen and lithium atoms produces an oxygen- and lithium-deficient surface skin characterized by high densities of oxygen vacancies (VO) and the reduction of pentavalent niobium (Nb5+) to lower oxidation states (Nb4+ and Nb3+)
3. While thermal annealing repairs crystallographic point defects, it cannot remove insoluble reaction byproducts or eliminate line-edge striations transferred from the lithography mask
4. Selective chemical wet etching provides a targeted means of stripping defective surface crusts and smoothing the etched waveguide facets
5. In the chemical treatment table, Standard Clean 1 (SC-1) is used at an operating temperature of 70°C - 80°C
6. In the chemical treatment table, Standard Clean 1 (SC-1) targets sub-stoichiometric surface crust, oxygen-vacancy-rich skin, and organic particles
7. In the chemical treatment table, Standard Clean 1 (SC-1) provides controlled sub-nanometer surface stripping without undercutting the bulk core
8. The implementation of an SC-1 clean (NH4OH:H2O2:H2O) addresses both particulate contamination and surface stoichiometry.
9. The alkaline peroxide mixture lifts off insoluble redeposited submicron debris through simultaneous surface oxidation and electrostatic double-layer repulsion.
10. Furthermore, plasma bombardment leaves a shallow, highly defective surface layer characterized by high oxygen vacancy concentrations.
11. SC-1 gently dissolves this vacancy-rich sub-stoichiometric boundary layer.
12. Removing this defective layer prevents anomalous under-etching during downstream processing and promotes strong adhesion for subsequent dielectric films, suppressing pattern peeling and delamination at submicron scales.
13. The choice of reactive gas chemistry controls etch selectivity, sidewall profile angle, and the accumulation of non-volatile surface products.
14. This suppresses sidewall fencing, achieves steep sidewall profiles (>80°-83°), and yields etch selectivities above 1.4:1 relative to SiO2 hard masks.
15. Operating at low chamber pressures (1.5 mTorr-3.0 mTorr) expands the ion mean free path and narrows the ion angular distribution across the plasma sheath.
16. A subsequent pulse of low-energy ions (for example, Ar+ with bias energies below the bulk sputtering threshold, <50 eV) or a reactive ligand selectively desorbs the modified surface layer while leaving the underlying crystalline lattice unperturbed.
17. ALE demonstrated on metal oxides and lithium niobate achieves an etch per cycle of 1.5 to 1.8 A/cycle with over 95% synergy, producing atomically smooth surface finishes without introducing sub-surface damage layers.
18. Etch + Chemical Treatment (SC-1 Clean + Dilute BOE Strip) has a typical sidewall RMS roughness of 0.5 - 1.0 nm.
19. Immersion in an SC-1 bath (\(\text{NH}_4\text{OH}:\text{H}_2\text{O}_2:\text{H}_2\text{O} = 1:1:5\)) at \(70^\circ\text{C}\) for \(10\) minutes gently removes the oxygen-vacancy-rich surface crust and lifts off redeposited particulate debris
</statements>

Begin the assessment now. Output only the JSON list, without any conversational text or explanations.